Measurement Computing BTH-1208LS User manual

BTH-1208LS
Wireless Multifunction DAQ Device
Document Revision 1
August 2013
© Copyright 2013
User's Guide
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

HM BTH-1208LS
Your new Measurement Computing product comes with a fantastic extra —
Management committed to your satisfaction!
Thank you for choosing a Measurement Computing product—and congratulations! You own the finest, and you can now enjoy
the protection of the most comprehensive warranties and unmatched phone tech support. It’s the embodiment of our mission:
To provide data acquisition hardware and software that will save time and save money.
Simple installations minimize the time between setting up your system and actually making measurements. We offer quick and
simple access to outstanding live FREE technical support to help integrate MCC products into a DAQ system.
Limited Lifetime Warranty: Most MCC products are covered by a limited lifetime warranty against defects in materials or
workmanship for the life of the product, to the original purchaser, unless otherwise noted. Any products found to be defective in
material or workmanship will be repaired, replaced with same or similar device, or refunded at MCC’s discretion. For specific
information, please refer to the terms and conditions of sale.
Harsh Environment Program: Any Measurement Computing product that is damaged due to misuse, or any reason, may be
eligible for replacement with the same or similar device for 50% of the current list price. I/O boards face some harsh
environments, some harsher than the boards are designed to withstand. Contact MCC to determine your product’s eligibility for
this program.
30 Day Money-Back Guarantee: Any Measurement Computing Corporation product may be returned within 30 days of
purchase for a full refund of the price paid for the product being returned. If you are not satisfied, or chose the wrong product by
mistake, you do not have to keep it.
These warranties are in lieu of all other warranties, expressed or implied, including any implied warranty of merchantability or
fitness for a particular application. The remedies provided herein are the buyer’s sole and exclusive remedies. Neither
Measurement Computing Corporation, nor its employees shall be liable for any direct or indirect, special, incidental or
consequential damage arising from the use of its products, even if Measurement Computing Corporation has been notified in
advance of the possibility of such damages.
Trademark and Copyright Information
Measurement Computing Corporation, InstaCal, Universal Library, and the Measurement Computing logo are either trademarks
or registered trademarks of Measurement Computing Corporation. Refer to the Copyrights & Trademarks section on
mccdaq.com/legal for more information about Measurement Computing trademarks. Other product and company names
mentioned herein are trademarks or trade names of their respective companies.
© 2013 Measurement Computing Corporation. All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form by any means, electronic, mechanical, by photocopying, recording, or otherwise
without the prior written permission of Measurement Computing Corporation.
Notice
Measurement Computing Corporation does not authorize any Measurement Computing Corporation product for use
in life support systems and/or devices without prior written consent from Measurement Computing Corporation.
Life support devices/systems are devices or systems that, a) are intended for surgical implantation into the body, or
b) support or sustain life and whose failure to perform can be reasonably expected to result in injury. Measurement
Computing Corporation products are not designed with the components required, and are not subject to the testing
required to ensure a level of reliability suitable for the treatment and diagnosis of people.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

3
Table of Contents
Preface
About this User's Guide .......................................................................................................................5
What you will learn from this user's guide .........................................................................................................5
Conventions in this user's guide .........................................................................................................................5
Where to find more information.........................................................................................................................5
Chapter 1
Introducing the BTH-1208LS................................................................................................................6
Device features...................................................................................................................................................6
Functional block diagram...................................................................................................................................7
Chapter 2
Installing a BTH-1208LS .......................................................................................................................8
What comes with your shipment?.......................................................................................................................8
Hardware .......................................................................................................................................................................... 8
Software............................................................................................................................................................................ 8
Documentation.................................................................................................................................................................. 8
Unpacking...........................................................................................................................................................8
Installing the software ........................................................................................................................................8
Installing in a Windows environment............................................................................................................................... 8
Running and deploying apps in an Android environment ..................................................................................8
Pairing with the host device................................................................................................................................8
Installing the hardware in USB mode (Windows only)......................................................................................9
Configuring Bluetooth settings...........................................................................................................................9
Calibrating the hardware...................................................................................................................................10
Factory calibration...........................................................................................................................................................10
Field calibration...............................................................................................................................................................10
Chapter 3
Functional Details ...............................................................................................................................11
Analog input acquisition modes .......................................................................................................................11
Software paced mode.......................................................................................................................................................11
Continuous scan mode.....................................................................................................................................................11
Burst scan ........................................................................................................................................................................12
BTH-1208LS components................................................................................................................................12
USB connector.................................................................................................................................................................12
Power/pairing button........................................................................................................................................................13
LEDs................................................................................................................................................................................13
Screw terminals................................................................................................................................................................14
Signals ..............................................................................................................................................................15
Analog input....................................................................................................................................................................15
Analog output ..................................................................................................................................................................16
External clock input.........................................................................................................................................................16
Digital I/O........................................................................................................................................................................17
External pull-up capability...............................................................................................................................................17
Trigger input....................................................................................................................................................................18
Counter input...................................................................................................................................................................18
Ground.............................................................................................................................................................................18
Power output....................................................................................................................................................................18
Mechanical drawings........................................................................................................................................19
Chapter 4
Specifications......................................................................................................................................20
Analog input.....................................................................................................................................................20
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide
4
Accuracy..........................................................................................................................................................................21
Noise performance...........................................................................................................................................................21
Analog output...................................................................................................................................................22
Digital input/output...........................................................................................................................................22
External trigger.................................................................................................................................................23
External clock input..........................................................................................................................................23
Counter.............................................................................................................................................................24
Memory ............................................................................................................................................................24
Microcontroller.................................................................................................................................................24
Power................................................................................................................................................................25
Bluetooth ..........................................................................................................................................................25
USB ..................................................................................................................................................................25
Environmental ..................................................................................................................................................25
Mechanical .......................................................................................................................................................25
Signal connector...............................................................................................................................................26
Screw terminal pinout.......................................................................................................................................26
Differential mode pinout..................................................................................................................................................26
Single-ended mode pinout ...............................................................................................................................................26
Declaration of Conformity..................................................................................................................27
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

5
Preface
About this User's Guide
What you will learn from this user's guide
This user's guide describes the Measurement Computing BTH-1208LS wireless data acquisition device and lists
device specifications.
Conventions in this user's guide
For more information
Text presented in a box signifies additional information and helpful hints related to the subject matter you are
reading.
Caution! Shaded caution statements present information to help you avoid injuring yourself and others,
damaging your hardware, or losing your data.
bold text Bold text is used for the names of objects on a screen, such as buttons, text boxes, and check boxes.
italic text Italic text is used for the names of manuals and help topic titles, and to emphasize a word or phrase.
Where to find more information
Additional information about the BTH-1208LS is available on our website at www.mccdaq.com. You can also
contact Measurement Computing Corporation by phone, fax, or email with specific questions.
Knowledgebase: kb.mccdaq.com
Phone: [phone] and follow the instructions for reaching Tech Support
Fax: [phone] to the attention of Tech Support
Email: [e-mail]
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

6
Chapter 1
Introducing the BTH-1208LS
The BTH-1208LS is a multifunction data acquisition device that communicates using Bluetooth® wireless
technology.
The device is supported under the following operating systems:
Microsoft® Windows® 8/7/Vista® (SP2)/XP (SP3) (32-bit or 64-bit)
Android™ 3.1 or later
The Bluetooth radio host used with the device must support Bluetooth 2.0 or later. The following Bluetooth
stack protocols are supported on Windows:
Microsoft Bluetooth stack
Broadcom ® Bluetooth stack (not supported by Windows XP SP3)
The device supports USB 2.0 full-speed when connected to a USB port. The device is also compatible with
USB 1.1 ports; however, the speed of the device may be limited when using a USB 1.1 port due to the
difference in transfer rates on USB 1.1 versions of the protocol (low-speed and full-speed).
Device features
The BTH-1208LS provides the following features:
Eight 11-bit single-ended (SE) or four 12-bit differential (DIFF) analog input channels
1 kS/s max sampling rate in Bluetooth continuous scan mode
50 kS/s sampling rate in Bluetooth burst I/O mode and when communicating over USB connection
Software-selectable analog input ranges of ±10 V (SE), and ±20 V, ±10 V, ±5 V, ±4 V, ±2.5 V, ±2.0 V,
±1.25 V, and ±1.0 V (DIFF).
Two 12-bit analog outputs
Eight individually-configurable digital I/O channels
One 32-bit event counter
One external digital trigger input
One external clock input
Two screw terminal connectors for field wirings
Powered by two AA batteries (standard or rechargeable) when in Bluetooth mode; can also be powered by
a USB power supply in Bluetooth mode or from the USB host in USB mode
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Introducing the BTH-1208LS
7
Functional block diagram
BTH-1208LS functions are illustrated in the block diagram shown here.
Figure 1. Functional block diagram
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

8
Chapter 2
Installing a BTH-1208LS
What comes with your shipment?
Verify that the following hardware components are included in the shipment:
Hardware
BTH-1208LS
USB cable
Two rechargeable AA NiMh batteries
Software
MCC DAQ CD
Documentation
MCC DAQ Software Quick Start Guide
The Quick Start Guide booklet provides an overview of the MCC DAQ software you received with the
device, and includes information about installing the software. Please read this booklet completely before
installing any software or hardware.
BTH-1208LS Quick Start
Unpacking
As with any electronic device, take care while handling to avoid damage from static electricity. Before
removing the BTH-1208LS from its packaging, ground yourself using a wrist strap or touch either the computer
chassis or other grounded object to eliminate any stored static charge.
If the device is damaged, notify Measurement Computing Corporation immediately.
Installing the software
Installing in a Windows environment
Refer to the Quick Start Guide that ships with your device for instructions on installing the MCC DAQ software
in a Windows environment. This booklet is available in PDF at www.mccdaq.com/PDFmanuals/DAQ-
Software-Quick-Start.pdf.
Running and deploying apps in an Android environment
For instructions on deploying and running apps in an Android environment, refer to the UL for Android
Example Projects topic in the Universal Library for Android Help that installs with the UL for Android
software library on the MCC DAQ CD.
Pairing with the host device
Pairing creates a bond between a Bluetooth device and a host device. A host device can be either a Windows-
based computer or an Android device (tablet, phone, or mini-PC).
The BTH-1208LS must be paired with the host device before it can establish a wireless connection and transmit
acquired data to the device. A BTH-1208LS only has to be paired once with a particular host device.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Installing a BTH-1208LS
9
The BTH-1208LS can be paired or connected when powered by:
batteries (standard or rechargeable)
an external USB power supply
The BTH-1208LS cannot be paired when powered by a USB host device.
To pair the BTH-1208LS as a Bluetooth device, make sure the device is not connected to a USB host, and
complete the following steps (refer to Figure 2 on page 12 for the location of device components referenced in
this section):
1. Make sure the host device is configured to host a Bluetooth device. Refer to host device documentation to
learn how to enable Bluetooth and how to search for and pair with Bluetooth devices.
2. If powered by batteries, press and hold the button for at least five seconds to power on the device and put it
into pairing mode.
If powered by a USB power supply, press and hold the button for at least three seconds to put it into
pairing mode.
When the Power and Status LEDs blink alternately, the device is in pairing mode and is ready to pair with
the host device.
3. Select the Bluetooth device setup in the host device OS software, and then select the BTH-1208LS when it
displays. Refer to the Bluetooth documentation of your host device to learn how to pair it with a Bluetooth
device.
For example, in Windows, select Bluetooth Devicefrom the Control Panel, and then double-click on
BTH-1208LS-xxxx in the Add a device dialog box (xxxx are the last four digits of the device serial
number. You may need to wait a few seconds for the device to display.
4. If host device requests a passkey, PIN or pairing code, enter the default value for the device (0000).
5. Press and hold the power/pairing button for two seconds to remove the device from pairing mode.
Once the BTH-1208LS is paired to the host device, run an application that communicates with the device (such
as InstaCal) to establish a connection. The Status LED turns on to indicate a Bluetooth connection is
established.
Note 1: Measurement Computing recommends that you connect one of the digital grounds (GND) to earth
ground to reduce the chance of the BTH-1208LS unexpectedly powering down due to electrostatic
discharge.
Installing the hardware in USB mode (Windows only)
The driver needed to run the BTH-1208LS device is installed when you install the software. Therefore, you
need to install the software package you plan to use before you install the hardware. For operation on a
Windows operating system, Measurement Computing recommends that you run Windows Update to update
your operating system with the latest USB drivers.
Connect the USB cable to an available USB port on the computer or to an external USB hub connected to the
computer. Connect the other end of the USB cable to the USB connector on the device. No external power is
required.
Configuring Bluetooth settings
All Bluetooth settings except for the pairing code can be changed when the BTH-1208LS is either physically or
wirelessly connected to the host device. The pairing code can only be changed when the BTH-1208LS is
physically connected to the host device.
You can configure the following Bluetooth settings on the BTH-1208LS through software. For example, if you
are using the device in a Windows environment, you can configure these settings with InstaCal.
Pairing code – Four digit code that identifies the BTH-1208LS to the host device (default = 0000). The
pairing code cannot be changed when the BTH-1208LS is connected wirelessly to the host device.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Installing a BTH-1208LS
10
Bluetooth connection status notifications – You can set values that indicate when the device is
connected over Bluetooth, and when the Bluetooth connection terminates. Connected and disconnected
values can be set for digital outputs, analog output channel 0, and analog input channel 1
Auto shutdown – When the device is powered by batteries, you can configure the device to power down a
specified amount of time after the Bluetooth connection terminates.
Battery charging – When the device is powered by rechargeable batteries, you can configure the device to
recharge batteries from the USB power supply when connected over Bluetooth.
Calibrating the hardware
Factory calibration
The Measurement Computing Manufacturing Test department performs the initial factory calibration. Return
the device to Measurement Computing Corporation when calibration is required. The recommended calibration
interval is one year.
Field calibration
Field calibration is not supported.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

11
Chapter 3
Functional Details
Analog input acquisition modes
The BTH-1208LS can acquire analog input data in three different modes – software paced, continuous scan, and
burst scan.
Software paced mode
In software paced mode you can acquire one analog sample at a time. You initiate the A/D conversion by
calling a software command. The analog value is converted to digital and returned to the computer. You repeat
this procedure until you have the total number of samples that you want from one channel.
When communicating over a Bluetooth connection, the typical throughput sample rate in software paced
mode is 10 S/s (system-dependent).
When communicating over a USB connection, the typical throughput sample rate in software paced mode
is 250 S/s (system-dependent).
Continuous scan mode
In continuous scan mode you can acquire data from up to eight channels. The analog data is continuously
acquired and converted to digital values until you stop the scan.
When communicating over a Bluetooth connection, the maximum continuous scan rate of 1024 S/s is an
aggregate rate. The total acquisition rate for all channels cannot exceed 1024 S/s. The following table lists
the scan rates when scanning from one to eight channels in Bluetooth mode.
Maximum continuous scan rate in Bluetooth mode
# channels scanned Scan rate (S/s)
1 1024
2 512
3 341.33
4 256
5 204.8
6 170.67
7 146.28
8 128
When communicating over a USB connection, the maximum continuous scan rate of 50 kS/s is an
aggregate rate. The total acquisition rate for all channels cannot exceed 50 kS/s. Data is transferred in
blocks of 32 samples from the device to the memory buffer on your computer.
The following table lists the scan rates when scanning from one to eight channels in USB mode.
Maximum continuous scan rate in USB mode
# channels scanned Scan rate (kS/s)
1 50
2 25
3 16.70
4 12.50
5 10
6 8.30
7 7.14
8 6.25
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
12
In both Bluetooth mode and USB mode, you can start a hardware paced continuous scan with either a software
command or with an external hardware trigger event.
Burst scan
In burst scan mode (BURSTIO) you can acquire data at the maximum throughput of 50 kS/s from the
BTH-1208LS when connected in Bluetooth mode. BURSTIO doesn’t offer any advantage in USB mode, since
these rates are supported for BLOCKIO in USB mode.
Sample sizes are limited to the size of the FIFO (12288 samples) in BURSTIO mode. The acquired data is read
from the FIFO and transferred to a user buffer in the computer. You can initiate a single acquisition sequence of
one to eight channels with either a software command or an external hardware trigger event.
Burst scans are limited to the depth of the on-board memory, as the data is acquired at a rate faster than it can be
transferred to the computer. Keep in mind that when using Bluetooth, the rate of transfer of the acquired data to
the host is still limited, so the process can take several seconds. Time must be allowed between scans for the
acquisition AND the transfer of the data.
The maximum sampling rate is an aggregate rate. The total sample rate using burst scan mode is 50 kS/s per
channel for any or all channels. An error occurs if you exceed the FIFO capacity and acquire more than12,288
samples in BURSTIO mode.
BTH-1208LS components
These BTH-1208LS components are shown in Figure 2.
Screw terminal connectors
USB connector
Power/pairing button
LED indicators (Status and Power)
1 Screw terminals for digital I/O, digital trigger, power
out, clock input, and counter input 4 Power/pairing button
2 Screw terminals for analog input and analog output 5 Power LED (top) and Status
LED (bottom)
3 USB connector
Figure 2. Components
USB connector
The USB connector provides 5 V power when connected to a USB power supply, and provides both power and
communication when the device is connected to a USB port. If rechargeable NiMH or NiCd batteries are
installed, batteries recharge when the device is connected to a USB host or power supply.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
13
Power/pairing button
The power/pairing button has different functions depending on the power source of the device.
The term pairing refers to one function of the button – to put the device in pairing mode so it can establish an
association between the Bluetooth radio on the host device and the BTH-1208LS radio.
Button functions are listed in the table below.
Power/pairing button functions
Power Status Button Functions
Battery powered 
To power on the device, press and hold the button for 3 seconds. To enter pairing
mode, hold the button for an additional 2 seconds.
To remove the device from pairing mode, press and hold the button again for 2
seconds.
To power off the device when not in pairing mode, press and hold the button for 2
seconds
Powered by USB charger/USB
power supply

To put the device in pairing mode when it is powered on, press and hold button for 2
seconds.
To remove the device from pairing mode, press and hold the button again for
2 seconds.
Powered by USB host port or
hub The power/pairing button is disabled.
LEDs
The Power LED indicates the power status of the device. The Status LED indicates the communication status of
the device.
LEDs cannot be disabled. LED states are listed in the tables below.
Power and Status LED behavior
Power LED Indication
Steady green The device is powered by USB and the batteries are sufficiently charged or not installed.
Blinks
continuously

If the device is connected to USB port/host, then the batteries are recharging (only if rechargeable
batteries are installed).
If the device is not connected to USB port, then it is powered by batteries.

If the Power LED is blinking alternately with the Status LED, then the device is in pairing mode.
Off Device is off.
Status LED Indication
Steady green Bluetooth or USB connection established
Blinks
continuously

Communication with host computer occurring over Bluetooth or USB connection.
If the Status LED is blinking alternatively with the Power LED, then device is in pairing mode.
Off A Bluetooth or USB connection is not established
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
14
Screw terminals
The screw terminals provide the followings:
Eight analog inputs (CH0H/CH0L to CH3H/CH3L)
Two analog outputs (AOUT0and AOUT1)
Eight digital I/Os (DIO0to DIO7)
One external trigger input (TRIG)
One external counter input (CTR)
One external clock input (AICKI)
One power output (+VO)
Six analog grounds (AGND)
Four digital grounds (GND)
Use 16 AWG to 30 AWG wire when makings to the screw terminals.
The single-ended mode pinout is shown in Figure 3.
Figure 3. Single-ended mode pinout
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
15
The differential mode pinout is shown in Figure 4.
Figure 4. Differential mode pinout
Signals
Analog input
You can connect up to eight single-ended analog inputs (CH0 to CH7) or four differentials (CH0H/CH0L to
CH3H/CH3L).
Single-ended configuration
When configured for single-ended input mode, eight analog input channels are available. Each analog input has
11-bit resolution (due to restrictions imposed by the A/D converter) and offers a ±10 V analog input range.
The input signal is referenced to signal ground (AGND), and is delivered through two wires:
Connect the wire carrying the signal to be measured to CHx.
Connect the second wire to AGND.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
16
Single-ended measurements using differential channels
To perform a single-ended measurement using differential channels, connect the signal to the CHxHinput, and
ground the associated CHxL input.
Differential configuration
When the analog input channels are configured for differential input mode, four analog input channels are
available. A low-noise precision programmable gain amplifier (PGA) is available on differential channels. Each
analog input has 12-bit resolution and offers software-selectable analog input ranges of ±20 V, ±10 V, ±5 V,
±4V, ±2.5 V, ±2.0 V, ±1.25 V, and ±1.0 V.
In differential mode, the input signal is measured with respect to the low input, and is delivered through three
wires:
Connect the wire carrying the signal to be measured to CHxH.
Connect the wire carrying the reference signal to CHxL.
Connect the third wire to AGND.
In differential mode, the following two requirements must be met for linear operation:
Any analog input must remain in the −10 V to 20 V range with respect to ground at all times.
The maximum differential voltage on any analog input pair must remain within the selected voltage range.
Channel gain queue
The channel gain queue feature allows you to set up a scan sequence with a unique per-channel gain setting and
channel sequence. The gain settings are stored in a channel-gain queue list that is written to local memory on
the device.
The channel-gain queue list can contain up to up to 8 elements in single-ended mode or four elements in
differential mode. The elements must be unique and listed in ascending order. An example of a three-element
list is shown in the table below.
Sample channel gain queue list
Element Channel Range
0 CH0 BIP10V
1 CH2 BIP5V
2 CH3 BIP10V
When a scan begins with the gain queue enabled, the BTH-1208LS reads the first element, sets the appropriate
channel number and range, and then acquires a sample. The properties of the next element are then retrieved,
and another sample is acquired. This sequence continues until all elements in the gain queue have been selected.
When the end of the channel list is detected, the sequence returns to the first element in the list. This sequence
repeats until the specified number of samples is acquired.
Carefully match the gain to the expected voltage range on the associated channel or an over range condition
may occur. Although this condition does not damage the device, it does produce a useless full-scale reading,
and can introduce a long recovery time due to saturation of the input channel.
Analog output
Two 12-bit analog outputs are available at AOUT0 and AOUT1.
Each analog output channel has an output range of 0 V to 2.5 V. Throughput is system-dependent.
The D/A is software paced.
External clock input
Connect an external clock signal to AICKI to pace input scanning operations.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
17
Digital I/O
You can connect up to eight digital I/O lines to DIO0 through DIO7. When configured for input, the digital
terminals can detect the state of any TTL-level input.
Digital input voltage ranges of up to 0 to 5.5 V are permitted, with thresholds of 0.8 V (low) and 2.0 V (high).
Each DIO channel is an open-drain, which can sink up to 50 mA for direct drive applications when used as an
output.
Figure 5 shows an example of a typical digital output connection.
Figure 5. Digital output connection (typical)
External pull-up capability
Inputs are pulled high by default to 3.3 V through 47.5 kΩ resistors on the circuit board. The pull-up voltage is
common to all 47.5 kΩ resistors.
You can place an external pull-up resistor on any of the DIO bits in order to limit source current to less than 50
mA., which requires a 100 Ωresistor minimum. A 2 kΩor 5 kΩresistor would be typically used, allowing for a
1 mA current
You can also use an external pull-up resistor to pull the DIO bit up to a voltage that exceeds the internal 3.3 V
pull-up voltage (5.5 V maximum).
When using external pull-up resistors, be aware that the internal resistors cause a slight voltage shift to digital
lines in the on state as various lines change between the on/off states.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
18
Figure 6. Digital I/O external resistor configuration
Trigger input
The TRIG_IN pin is an external digital trigger input that you can configure for either rising/falling edge, or
high/low level.
Counter input
The CTR pin is a 32-bit event counter that can accept frequency inputs up to 1 MHz. The internal counter
increments when the TTL levels transition from low to high.
Ground
The analog ground (AGND) pin provide a common ground for all analog channels. The digital ground (GND)
pins provide a common ground for the digital, trigger, counter, and power terminals.
Power output
The +VO pin is a 3.3 volt output that can source up to 50mA that is supplied by the power source of the device.
You can use this terminal to power external devices or circuitry.
Caution! The +V0 pin is an output. Do not connect to an external power supply or you may damage the
BTH-1208LS and possibly the computer.
For more information about signals
For more information about analog and digital signals, refer to the Guide to DAQ Signal Connectionsat
www.mccdaq.com/pdfs/DAQ-Signal-Connections.pdf.
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

BTH-1208LS User's Guide Functional Details
19
Mechanical drawings
Figure 7. Housing and circuit board dimensions
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com

20
Chapter 4
Specifications
All specifications are subject to change without notice.
Typical for 25°C unless otherwise specified.
Specifications in italic text are guaranteed by design.
Analog input
Table 1. Analog input specifications
Parameter Condition Specification
A/D converter type Successive approximation type
Input voltage range for linear operation CHx to GND Single-ended mode: ±10 V max
Differential mode: –10 V min, 20 V max
Absolute maximum input voltage
CHx to GND
±25 V max
Input impedance 140 kΩ
Input current (Note 1) Vin = +10 V 70 µA typ
V
in
= 0 V –12 µA typ
Vin = –10 V –94 µA typ
Number of channels 8 single-ended or 4 differential; software-selectable
Input ranges Single-ended ±10 V, G=2
Differential ±20 V, G=1
±10 V, G=2
±5 V, G=4
±4 V, G=5
±2.5 V, G=8
±2.0 V, G=10
±1.25 V, G=16
±1.0 V, G=20
Software-selectable
Throughput (Note 2) Software paced 10 S/s typ, system-dependent (Bluetooth)
250 S/s typ, system-dependent (USB)
Continuous scan 0.014 S/s to 1024 S/s (Bluetooth)
0.014 S/s to 50 kS/s (USB)
Burst 0.014 S/s to 50 kS/s to 12K (12,288) sample FIFO
Transfer rate to host is limited to 1024 S/s
(Bluetooth)
Channel gain queue Software selectable. 8 elements in SE mode,
4 elements in DIFF mode.
One gain element per channel. Elements must be
unique and listed in ascending order.
Resolution (Note 3) Differential 12 bits, no missing codes
Single-ended 11 bits
Integral linearity error ±1 LSB typ
Differential linearity error ±0.5 LSB typ
Repeatability ±1 LSB typ
Trigger source Software-selectable External digital: TRIG_IN
Software-selectable
Pacer source Software-selectable 
Internal
External (AICKI), rising edge triggered
Software-selectable
Distributed By MicroDAQ, LLC 603-746-5524 www.MicroDAQ.com