Upcycled STIB Validator

1. The Challenge
2. Big Picture
3. Realization
4. Hardware Note
   1. Microcontroller
   2. Screen
   3. Keyboard
5. Schematic
6. PCB

The Challenge

The initial challenge was to reuse a decommissioned STIB validator and turn it into something useful

Big Picture

Most mornings, when I arrive near the tram stop on my way to work, I have to run (uphill) so I don’t miss the tram.

If I had left home in time, 2 or 3 minutes earlier, I wouldn’t have had to run.

Without having to look at my phone every 2 minutes, I wanted to know when to leave the house to make sure I wouldn’t miss the tram or have to run. So the idea was simply to know when the trams would arrive at the stop.

What could be more elegant than a validator to inform me of the tram’s arrival in real time?

Realization

This is a work in progress, it will most certainly never be finished.

The information is given as an inspiration and does not pretend to give any functional result.

Some of the information may be incorrect or obsolete.

I do it for fun, for the challenge and to keep learning…

List of Features

Here’s what I would like the machine to do. Not all the features have been achieved yet.

• Retrieve data in real time from the STIB API.
• Display useful information in a not too ugly way.
• Automatic sleep mode.
• Using the validator’s keyboard to wake up, switch screens, etc
• Minimum consumption.
• List the stops that are close to the wifi connection point.
• Buzz when we have to leave home to be in time.
• …

Hardware Notes

Microcontroller

As a microcontroller, I used the one I had left: NodeMCU-32S

The board embeds an ESP-WROOM-32 from Espressif

Some more information about used µController board

Screen

• Dimension: 240x128
• Product ref: RG240128B-BIW-V
• LCD
• STN Negative
• blue
• LED
• PIN: 20
• ROHS
• Manufacturer: RAYSTAR OPTRONICS

RG240128B-BIW-V product’s Details

RA6963 Controller Screen pin description

pin		notes
1	VSS	Ground (0V)
2	VDD	Logic Supply Voltage (+3V)
3	VO	Contrast Adjustment
4	C/D	if /WR == L
		set C/D to H for Command Write
		set C/D to L for Data Write
		if /RD == L
		set C/D to H for Status Read
		set C/D to L for Data Read
5	/RD	Read data when RD = L
6	/WR	Write data when WR = L
7~14	DB0 - DB7	Data Bus Line
15	/CE	Chip Enable
16	/RES	Reset: H = Normal, L = Initialize RA6963
17	VEE	Negative Power Supply (-20V)
18	MD2	H:32 columns; L:40 columns
19	FS1	FS : Pin for selection of font
		H = Font 6×8 (default)
		L = Font 8×8
20	NC	no connection

pin		notes
19	LEDA	LED back-light Power Supply + (4.05V)
20	LEDK	LED back-light Power Supply - (4.05V)

ESP-32S to RA6963 wiring

ESP-32S GPIO	ESP-32S Board pin	RA6963 raw pin	RA6963 logic	U8glib
-	-	1	VSS	-
-	-	2	VDD	-
-	-	3	VO	-
17	28	4	C/D	dc
-	-	5	/RD	-
16	27	6	/WR	enable
32	13	7	DB0	d0
33	12	8	DB1	d1
25	11	9	DB2	d2
26	10	10	DB3	d3
27	9	11	DB4	d4
14	8	12	DB5	d5
12	7	13	DB6	d6
13	5	14	DB7	d7
4	26	15	/CE	cs
15	23	16	/RES	reset
-	-	17	VEE	-
-	-	18	MD2	-
-	-	19	FS1	-
-	-	20	NC	-

ESP-32S GPIO	ESP-32S Board pin	RA6963 raw pin	RA6963 logic	U8glib
2	24	-	LEDA	-
-	-	-	LEDK	-

U8g2 Library

RG240128B is just a standard R6963 GLCD.

U8g2 library works with this display.

U8g2 & RA6963

u8g2: U8glib library for monochrome displays, version 2

U8g2 library wiki

C++ setup & wiring

• RA6963 is a t6963 controler type.
• Display is 240x64
• 8-bit parallel interface using the 8080 protocol

1. Page buffer Use 240 bytes of RAM

   U8G2_T6963_240X64_1_8080(rotation, d0, d1, d2, d3, d4, d5, d6, d7, enable, cs, dc [,reset])
   

   Only one page of the display memory is stored in the microcontroller RAM. Use a firstPage()/nextPage() loop for drawing on the display.

2. Page buffer

   Use 480 bytes of RAM

   U8G2_T6963_240X64_2_8080(rotation, d0, d1, d2, d3, d4, d5, d6, d7, enable, cs, dc [,reset])
   

   Same as 1, but maintains two pages in the microcontroller RAM. This will be up to two times faster than 1.

3. full framebuffer

   Use 1920 bytes of RAM

   U8G2_T6963_240X64_F_8080(rotation, d0, d1, d2, d3, d4, d5, d6, d7, enable, cs, dc [,reset])
   

   Keep a copy of the full display frame buffer in the microcontroller RAM. Use clearBuffer() to clear the RAM and sendBuffer() to transfer the microcontroller RAM to the display.

   The full buffer F option can be used only if there is sufficient RAM available in the microcontroller.

   Use option 1 or 2 on a microcontroller with a small amount of RAM. The u8x8 API can be used if there is not even RAM for one page.

Rotation

Rotation/Mirror	Description
U8G2_R0	No rotation, landscape
U8G2_R1	90 degree clockwise rotation
U8G2_R2	180 degree clockwise rotation
U8G2_R3	270 degree clockwise rotation
U8G2_MIRROR	No rotation, landscape, display content is mirrored (v2.6.x)

physical bus selection

Graphics information has to be sent to the display. This information is received by the display controller through a physical bus (data lines), a communication protocol and a command sequence.

Often a display supports more than one physical bus. You have to select and setup the correct bus.

The physical bus is selected by connecting special pins to GND (Low) or +5V (High), often labeled as BS0, BS1 and BS2.

Read the datasheet of the display controller or the manual for instruction on how to setup a specific bus.

Sometimes the bus is just fixed and can not be changed.

Digital Line

The display must be connected to the board in order to transfer data from the board to the display.

Depending on the selected physical bus, several pins have to be connected to the outputs of the board.

In general, U8g2 can use any outputs of the board. So it does not matter which output pin is used (However it might be clever to select specific pins for hardware accelerated bus communication).

Voltage

ESP32 logic is 3.3V

RA6963 logic is 3.3v or 5V

So it can be used without Level shifter

Power Save Mode

Test of the power save mode from U8G2 is OK

cf. StibESP32/test_powerOff/test_powerOff.ino

Notes

• Connect FS to GND for U8glib, font select 8x8.
• Also note that you need a 10K variable pot with wiper at V0, one end at GND or VSS other end at -20V. Adjust the varpot so that V0 has around -12V to -15V.

• VCC = Collector supply Voltage
• VEE = Emitter supply
• VDD = Drain supply
• VSS = Source supply

Keyboard

The validator has a capacitive touch keyboard.

I’m not experienced enough to do reverse engineering, so I decided to redo a capacitive keyboard myself.

The result is not optimal and it could be improved, but it is functional enough.

//TODO: MPR121

https://github.com/adafruit/Adafruit_MPR121_Library

Global Pin use of the ESP-32S

ESP-32S GPIO	ESP-32S Board pin	Usage	Pin
VIN 3.3	19	VIN 3.3	-
EN	18	-	-
36	17	-	-
39	16	-	-
34	15	MPR121-IRQ	IRQ
35	14	-	-
32	13	RA6963-DB0	7
33	12	RA6963-DB1	8
25	11	RA6963-DB2	9
26	10	RA6963-DB3	10
27	9	RA6963-DB4	11
14	8	RA6963-DB5	12
12	7	RA6963-DB6	13
GND	6	GND	-
13	5	RA6963-DB7	14
9	4	-	-
10	3	-	-
11	2	-	-
VIN 5V	1	-	-

ESP-32S GPIO	ESP-32S Board pin	Usage	Pin
6	20	-	-
7	21	-	-
8	22	-	-
15	23	RA6963/RES	16
2	24	BackLight	-
0	25	Buzzer	-
4	26	RA6963/CE	15
16	27	RA6963/WR	6
17	28	RA6963/CD	4
5	29	µSD/CS	2
18	30	µSD/CLK	4
19	31	µSD/MISO	5
GND	32	-	-
21	33	MPR121-SDA	SDA
3	34	-	-
1	35	-	-
22	36	MPR121-SCL	SCL
23	37	µSD/MOSI	3
GND	38	-	-

Schematic

PCB