ST STM8T141-EVAL User manual

October 2010 Doc ID 15952 Rev 4 1/24
UM0742
User manual
STM8T141-EVAL evaluation kit
Introduction
The STM8T141-EVAL is an evaluation kit which introduces developers to
STMicroelectronics STM8T141 touch and proximity capacitive sensor.
It contains an STM8T141 evaluation board, the MB858, plus a set of preconfigured plug-in
modules which can evaluate STM8T141 device performances in either touch or proximity
detection (depending on the module which has been plugged in).
The evaluation kit features are the following:
■Touch detection with on-board PCB sensing electrode and 1.5 mm dielectric panel
■Easy dielectric adjustment by stacking acrylic panels
■Proximity detection with on-board PCB sensing electrode or plug-in antenna
■Standalone power configuration using an on-board battery
■External power supply through USB interface
■Electrode grounding or shielding configured by jumper
Table 1. STM8T141 main features
Features STM8T141
Sensing channel 1
Proximity detection range A few cm
Outputs 1 (Touch or Proximity)
Sampling capacitor External
Active shield Yes
VDD 2.0 to 5.5 V
IDD in Normal power mode (typ) 30 µA
IDD in Low power mode 11 µA
Packages SO8 narrow or UFDFPN8 (2 x 3 mm)
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Contents UM0742
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Contents
1 Description of the STM8T141-EVAL kit . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 MB858 evaluation board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.1 Module socket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1.2 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1.3 On-board sensing electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1.4 Antenna connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.1.5 Copper planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.2 STM8T141 plug-in modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Getting started with the MB858 evaluation board . . . . . . . . . . . . . . . . 11
2.1 Using the on-board sensing electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Installing an external shielded antenna . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3 Shielding and grounding configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5 Programming tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7 Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8 Reference documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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UM0742 List of tables
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List of tables
Table 1. STM8T141 main features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. STM8T141 configuration color coding and marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 3. Option bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 4. STM8T141 module pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 5. Copper plane configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 6. STM8T141 board in standalone mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 7. STM8T141 board powered through USB supply with earth connection . . . . . . . . . . . . . . . 15
Table 8. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 9. Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 10. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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List of figures UM0742
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List of figures
Figure 1. STM8T141-EVAL evaluation kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. MB858 evaluation board with STM8T141 module plugged-in . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 3. MB858 evaluation board top layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 4. MB858 evaluation board bottom layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 5. MB858 evaluation board top copper plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 6. MB858 evaluation board bottom copper plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 7. STM8T141 module assembly drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 8. On-board sensing electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 9. On-board sensing electrode configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 10. On-board sensing electrode with external antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 11. STM8T141 programming tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 12. STM8T141 blank module box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 13. STM8T141 evaluation board (MB858) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 14. STM8T141 module (MB856) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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UM0742 Description of the STM8T141-EVAL kit
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1 Description of the STM8T141-EVAL kit
The STM8T141-EVAL kit (see Figure 1) includes:
●1 STM8T141 evaluation board (MB858)
●4 STM8T141 preconfigured plug-in modules (MB856)
●1 antenna shielding cable
●1 additional 3 mm acrylic panel
Figure 1. STM8T141-EVAL evaluation kit
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Description of the STM8T141-EVAL kit UM0742
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1.1 MB858 evaluation board
Figure 2 shows the MB858 evaluation board, while Figure 3 and Figure 4 show the board
top and bottom layout.
Figure 2. MB858 evaluation board with STM8T141 module plugged-in
1. This photo is not contractual.
2. Pin 1 identifies the first pin of the module (refer to Table 4).
Figure 3. MB858 evaluation board top layout
Pin 1
STM8T141 module
MB858 evaluation board
Sensing electrode
DIP14 module
footprint
Antenna connector
Sensing electrode hatched copper
plane shield/grounding selection
Power supply switch
Current measurement
connector
GND Grab pin
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UM0742 Description of the STM8T141-EVAL kit
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Figure 4. MB858 evaluation board bottom layout
1.1.1 Module socket
The MB858 evaluation board features an SDIP14 socket to connect the STM8T141 module
(see Figure 3).
1.1.2 Power supply
The evaluation board can be powered by two different sources:
●A 6 V DC battery supply unit composed of two 3 V CR2016 batteries.
●A 5 V DC power supply delivered by the J1 USB connector (cable not provided) (see
Figure 4).
A dual-anode protection diode (D1) prevents power supply current injection.
IDD current can be monitored by connecting an ammeter to JP2 connector (see Figure 3).
Caution: Switch S1 power switch off to preserve batteries when the evaluation board is stored with a
module plugged into it.
1.1.3 On-board sensing electrode
A copper sensing plate deposited on the PCB is used as a sensing electrode for touch and
proximity detection (refer to Figure 3).
1.1.4 Antenna connector
JP1 connector allows to connect an external antenna instead of the on-board sensing
electrode.
USB power
connector
Battery socket
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1.1.5 Copper planes
Two copper planes (CP1, CP2) and one hatched copper plane (HCP) were laid out onto the
PCB (see Figure 5).
Figure 5. MB858 evaluation board top copper plane
Figure 6. MB858 evaluation board bottom copper plane
Top copper
plane (CP1)
Bottom
Hatched
copper plane (CP2)
copper plane
(HCP)
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UM0742 Description of the STM8T141-EVAL kit
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1.2 STM8T141 plug-in modules
The STM8T141-EVAL includes a set of plug-in modules (see Section 1.1). They allow a
quick and simple evaluation of the STM8T141 main features and performances for different
option byte configurations:
●3 modules configured in proximity mode / no marking
●1 module configured in sensitive touch mode / white marking
The modules incorporate one LED. To allow quick identification of the module configuration
(touch or proximity) when the demonstration is running, the following color codes are used:
●Blue LED corresponds to the proximity configuration
●Red LED corresponds to the touch configuration
Refer to Section 5 for information on programming tools.
The STM8T141 plug-in module PCB is green.
The STM8T141 touch/proximity output (TOUT/POUT) is connected to an LED which is
turned on when a touch or proximity detection occurs. The LED color depends on the
STM8T141 module configuration (refer to Ta bl e 2 and Figure 7). Refer to Ta ble 4 for the
description of STM8T141 module pins.
Table 2. STM8T141 configuration color coding and marking
PCB color Module configuration PCB marking LED color
Green Proximity detection No marking Blue
Sensitive Touch detection White dot ink marking Red
Table 3. Option bytes
Mode Sensitive touch description Standard proximity description
Power mode Low power mode with zoom Low power mode with zoom
Sensitivity threshold Sensitive touch Standard proximity
Recalibration timeout 15 seconds 15 seconds
TOUT/POUT output mode Active Active
Sampling conversion
period 20 ms 20 ms
Charge transfer frequency 125 kHz 125 kHz
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Description of the STM8T141-EVAL kit UM0742
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Figure 7. STM8T141 module assembly drawing
Table 4. STM8T141 module pin description
Pin number Pin name Description
1 SHOUT Shield output
2ELECElectrode
3 NC Not connected
4 TOUT/POUT Touch/Proximity output
5 NC Not connected
6CS
Capacitive sensing channel pin to external sampling
capacitance CS
7 VSS Ground
8 NC Not connected
9 CX Capacitive sensing channel pin to RX (CX serial resistor)
10 NC Not connected
11 NC Not connected
12 NC Not connected
13 VREG Internal voltage regulator output
14 NC Not connected
Touch/Proximity
output LED
Pin 1
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