TIX clock

Project TIX clock
Status	Stalled
Contact	Noor, bertrik
Last Update	2020-05-11

Have an 'original' TIX clock (YouTube video) from ThinkGeek.

Could also be programmed to display any number up to 4 digits, but the design is best suited for displaying time (blocks are in sets of 3, 9, 6, 9).

Reverse engineering

There are a total of 27 LEDs on the board, organised as 9 columns of 3 leds each. Each column has a shared cathode.

There are a total of 19 transistors on the board. Each column has its own transistor.

Schematic

File:TIX.pdf

Pins from this schematic:

• top row: RA0, pin 17
• mid row: RA1, pin 18
• bot row: RA2, pin 1
• col 1 (D19/D10/D1): RA6, pin 15
• col 2 (D20/D11/D2): RB7, pin 13
• col 3 (D21/D12/D3): RB6, pin 12
• col 4 (D22/D13/D4): RB5, pin 11
• col 5 (D23/D14/D5): RB4, pin 10
• col 6 (D24/D15/D6): RB3, pin 9
• col 7 (D25/D16/D7): RB2, pin 8
• col 8 (D26/D17/D8): RB1, pin 7
• col 9 (D27/D18/D9): RB0, pin 6

Software

Github archive for the software prototype is at https://github.com/bertrik/esptixclock

TODO

• wait for hardware to finish and update the pin map in display.cpp
• power it up, can we perhaps run the entire clock from USB 5V power?
• test it on actual hardware
• fancy startup animations / more display modes / etc

Basic principles

Basic principles of the software are:

• Inspired by the LichtKrant firmware
• Basic ESP32 Arduino framework
• Simple command interpreter running on the serial port @ 115200bps.
• TIX display driver that alternates between rows and lights up the pixels in the columns
• NTP client to get UTC time from NTP + local time conversion (incl. summer time)
• Main process to convert local time into TIX format (number of LEDs lit in a group indicates number)

Framerate calculation: At first I'm aiming at a 10 kHz line update rate (= interrupt rate). Suppose we have 3 rows, 4-bit intensity (16 levels) that means a worst case flicker is 10 kHz / 3 / 16 = 208 Hz. If this is still too low in practice, we can reduce the dimming resolution, or just use the LEDs at full brightness. In comparison, a MAX7219 has a "scan-rate" of 800 Hz typically.

Building

Arduino IDE

The software can be compiled in the Arduino IDE.

You need the ESP32 toolchain, see https://github.com/espressif/arduino-esp32/blob/master/docs/arduino-ide/boards_manager.md for the instructions.

Also install the following libraries:

• NtpClient, by Fabrice Weinberg, Sandeep Mistry

platformio

The software can be built and uploaded to the ESP32 using platformio:

 pio run -t upload

The ESP32 toolchain and required libraries will be automatically downloaded from the internet (and cached locally).

Platformio can be installed (on Debian Linux), using:

 sudo apt install python3-pip
 sudo pip3 install platformio

Add yourself to the 'dialout' group (and log out/in to activate):

 sudo adduser <yourlogin> dialout

Timeline

2019-11

Changed out the American plug for an EU one, but the clock requires 60 Hz AC, and 50 Hz will make it run slow and thus useless for telling time.

2020-01-17 - 2019-01-20

From an old Tweakers thread: "Dus schoef je wekker eens open en google op het typenummer van de chip. 10 tegen 1 dat er een 60/50Hz-select pootje aanzit. Vaak is die verbonden met een draadbruggetje op de print; omsolderen en klaar!"

Looked into this but no luck. Best bet is to replace the chip (original PIC16F628A, with ESP8266?) and update time via wifi.

Came across TIX-Uhr, describing improvements made to the (European version) TIX. Emailed and got the schematic from This Manhart.

Removed the original chip completely, to be replaced with an ESP32.

External links

• TIX-Uhr