THG TIM 2015 User manual

TIM 2015 Technical Manual v1 (February 2018) Page 1
TIM 2015 Speaking Clock
T CHNICAL MANUAL

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TIM 2015 is part
-
funded by the Telecommunications Heritage Group (THG and d
esigned by
WORK IN PROGR SS! A document of this kind is never entirely complete, so once the website is complete (www.TIM2015.uk) please
check for a newer version. Thank you for your understanding.
PL AS NOT : This is the Technical Manual . For setting up the clock after completion and information on the various methods of
synchronising the correct time please see the separate User Manua l document. The Assembly Manual explains how to construct TIM
2015.
Document doesn’t print properly?
All TIM 2015 documentation is produced in the DIN A4 format (8.2 " x 11.69"), which may cause problems when printing onto US Letter
size (8.5" x 11") paper. With Acrobat Reader for instance under Size Options, you will see four options: Fit, Actual size, Shrink oversized
pages and Custom Scale. One of these should work; we would suggest Shrink oversized pages, which will normally reduce the scale by a
few per cent and will not be very noticeable.
How to use this manual
This manual is written in something close to plain English and should be easy to follow (if not, tell us!). Yes, there’s a lot of it but you don’t
have to read it all in one session. The text is as comprehensive as possible, simply because not every constructor will be familiar with some
of the tasks.
 Important information is printed in bold type like this.
 Supplementary information that it is not essential to read the first time around, but could well be of value at a later stage, is printed in
panels (box-outs) with a grey background.

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The manual is arranged in numbered Chapters. The contents page follows.
And yes, there are a lot of words to read, simply because we tried to make the assembly process impossible to get wrong. Take it in stages if
you prefer.
Finally, if you get stuck, do try reading the manual a second time, perhaps more slowly. Things often become simpler to understand after
several readings. For a valuable and independent guide to using TIM 2015 please visit
http://www.samhallas.co.uk/repository/tim_2015.htm. Sam Hallas describes there how he built his own TIM 2015. It’s well worth reading!
User feedback
We welcome this! So if you have spotted a mistake in this manual, something you disagree with or else something you think could be
clarified, please get in touch. The same applies for anything you feel has been left out. Maybe you wish to comment on the product itself or
perhaps would like to suggest an improvement. Get in touch by an e-mail to [e-mail] . We’ll respond as soon as
humanly possible (but please bear in mind this is a spare-time activity).
Clarification
Here are three things that we need to stress in order to avoid any confusion.
Accuracy. The claim that we make for TIM 2015 is that it is accurate to within a second but no more. In other words, if you synchronise
TIM 2015 to a source of GPS signal or to a radio time signal transmitter such as MSF, DCF or WWVB, it is of ‘indicative’ but not ‘absolute’
accuracy, making it adequate for all everyday purposes.
Authenticity. The voice files used in TIM 2015 are all taken from recordings of actual speaking clocks, taken from a variety of sources. In
some cases the recordings were taken directly from the speaking clock apparatus with the agreement and kind cooperation of the museum
authorities involved. In other cases they were made from Internet files or tape recordings made in the past, processed for greater clarity as
necessary. The method in which the words, phrases and sounds are played out from digital media means the timing of the words may vary
very slightly from the timing of the original announcements but only by fractions of seconds and not in a way that users would detect.
Intellectual property. It is our understanding that all recordings used in TIM 2015 are in the public domain. They are provided in good faith
for non-commercial use, with no charge made to the end user other than the media on which they are recorded.

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Acknowledgments
Thanks to Dave Thorpe for his superb circuit design work, also to Mick Champion, Alan David, Mike Fletcher, Sam Hallas, Howard Harte,
John Nice, John Novack, Jayson Smith, Evan Stewart and Dave Whistler for their material assistance and inspiration. Photographs by Dave
Thorpe, Sam Hallas, David Henderson, Andrew Emmerson and the manufacturers and suppliers of various parts used. The computer-
engraved panels are produced for us by Architectural & Industrial Engravers, Northampton (http://www.aiengravers.co.uk/).
We suggest you print a hard copy of this document and keep it in a ring binder or one of those plastic display book folders
that you can buy at pound shops and in many supermarkets.
The latest version of this manual will be available to download at www.TIM2015.uk as soon as the website has been
created.
TIM 2015 IS DESIGNED
AND MADE IN BRITAIN

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Index to the sections of this manual
1. Technical description of TIM 2015
2. Diagnostic messages
3. Troubleshooting (problem solving)
4. Background information
5. Upgrades
6. The Catalex serial MP3 player
. Creating new ‘voices’ for TIM 2015
8. Revisions to this manual
9. Safety notice and legal disclaimer
Each section begins on a fresh page.
Please note that this is the Technical Manual. There is also a separate User Manual and also an Assembly Manual.

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Chapter 1 Technical description
People can use TIM 2015 very happily without reading anything in this manual! The information in this section is provided for people who
like to look ‘under the bonnet’ (British English) or ‘under the hood’ (US English) of TIM 2015.
How TIM 2015 works
The clock is controlled by a Microchip PIC18F25K22 microcontroller running encrypted assembler code at a clock speed of 32MHz from its
internal oscillator.
Timekeeping is provided by a Maxim DS3231 RTC (Real Time Clock) chip (fitted to module MOD3.) This chip has an integrated
temperature-compensated crystal oscillator (TCXO) and 32 68 kHz crystal for timekeeping accuracy of ±2ppm (or better) from 0°C to
+40°C. A long-life CR2032 lithium 3V coin cell maintains timekeeping during power failure.
The DS3231 communicates with the microcontroller using a serial I
2
C Interface and also provides a 1-second pulse to synchronise the voice
and time display updates (module MOD3 also contains a separate memory chip, which is not used).
The time of day speech announcements are handled by the Catalex player module (MOD4). This contains a dedicated YX5300 stereo audio
processor chip usually used for MP3 players. It also plays the WAV files used for the voice announcements in TIM 2015. The device
supports audio sampling frequencies of 8, 11.025, 12, 16, 22.05, 24, 32, 44.1 and 48 kHz.
Only one audio channel is being used for the mono recordings employed in TIM 2015. The microcontroller controls the Catalex player using
command strings sent at 9600 baud.
Voice files are stored as .WAV files (or .MP3 files) in folders on a microSD card. For each time-of-day announcement the microcontroller
compiles a list of required files and commands the Catalex module to play each file in sequence. The module reports when each file has
been played, ready for the microcontroller to request the next one.
The audio output from the Catalex player is filtered by an op-amp, IC3B (MC330 2), to reduce frequencies higher than 3,300Hz, as they lie
above the range of frequencies used for telephony.

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The audio is then passed to module MOD5 (Mitel 88422-3), which connects it to a telephone line (in the same way as a telephone answering
machine answers a call). This module a specialised telephone line interface to handle the transmission of audio, call ringing detection and
line seize/release. It isolates the phone line voltage and provides logic-level control lines for the microcontroller to detect incoming calls
(ringing) and answer/release them.
The audio announcements are also sent via a volume control (R26) to an audio power amplifier module (MOD6). This contains a PAM8403
stereo 3-watt Class D amplifier IC that lets you hear the announcements on a loudspeaker for quality monitoring and testing. This PAM8403
chip uses digital audio processing to achieve an efficiency of up to 90%, resulting in much reduced power consumption. Only one audio
channel of the amplifier is used because the sound in TIM 2015 is mono (not stereo).
The volume control also incorporates a switch output, which is inverted by transistor T5 to place the PAM8403 chip into very low power
shutdown mode (consuming less than 1µA) when the (switched) volume control is turned off. A separate part (IC3A) of the MC330 2 op-
amp provides an audio output for headphones, monitoring, etc. and has its own volume preset (R20).
A 128x64-pixel, ST 920-type LCD module (QC12864B) is used for the graphic display screen. It uses a 3-wire serial SPI interface to
communicate with the microcontroller. Display brightness is controlled using a PWM output from the microcontroller to driver transistor
T3.
The user interface is provided by a mechanical rotary encoder (with switch). When it is turned between each detent it sends a series of logic
level pulses via the two wires (A and B). By analysing the phase of these pulse edges the microcontroller determines the turn direction.
Power for the whole clock is provided by the 3-amp regulator module MOD1. This module contains an MP1584 switching regulator chip
running at around 1MHz for about 85% power efficiency with a 12V input. The high switching frequency should also reduce any EMI
interference that might otherwise degrade reception of radio time signal signals.
Transistor T4 periodically provides power to a small 3.3V regulator (IC1) under the control of the microcontroller. This 3.3V supply is
needed for the Wi-Fi module (MOD2) or can alternatively be used by an externally connected GPS module.
The Wi Fi module (MOD2) contains an ESP8266 processor that runs a program for handling the initial Wi-Fi configuration and then
periodically requesting the time from network servers. This Wi-Fi module uses a significant amount of power when active (about 200mA)
and although there is a low-power Sleep option, the module does not have the necessary Sleep pin connected to the header. This is resolved
by using transistor T4 to completely cut the 3.3V power when the module is not being used.
Communication is handled by a serial 3.3V logic link to the microcontroller. The module is not 5V-tolerant, requiring resistors R1 and R18
to lower the microcontroller output 5V logic levels to prevent damage to the Wi-Fi chip. Optional 30-second and serial time data outputs are

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provided. These are buffered by general-purpose transistors T1 and T2. A separate external interface and power supply will be needed if you
want to use these outputs for your own projects such as driving mechanical slave clocks or synchronising other devices.
Specifications
Power supply requirements:
9 - 12 Volts DC @ 1Amp rating (Switching type adapter preferred)
3 Volts lithium coin cell (CR2032) for the RTC timekeeping battery backup.
Power consumption:
 Approx 0.55W (Amplifier=off, Wi-Fi=off, Display brightness setting=34 (half-power).
 Approx 0. W (Amplifier=off, Wi-Fi=off, Display brightness setting=maximum brightness.
 Approx 1.14W (Amplifier=off, Wi-Fi=active, Display brightness setting=maximum brightness.
 Approx 2.35W (Amplifier=full volume (8Ω speaker), Wi-Fi=active, Display brightness setting=maximum brightness.
Backup timekeeping battery power consumption:
0.85µA (Estimated run-time >10 years (or the shelf life of the CR2032 battery)).
Dimensions:
PCB alone 140mm x 85mm x 1.6mm
Timekeeping accuracy:
Unadjusted RTC accuracy ±2ppm from 0°C to +40°C (about ± 5.4 seconds per month).
Timekeeping may be improved by timekeeping fine adjustment menu setting.
Crystal ageing:
First year: ±1ppm
1-10 Years: ±5ppm (RTC manufacturer’s estimate).

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Board dimensions (140 x 85mm)

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Board layout