3-flash

Flashing my firmware

Flash my own (test) firmware to the 303WIFILC01 clock.

Introduction

After having made a backup of the original firmware, and the analysis of the connections between the key components, I decided to take the plunge: flash my own firmware.

Hardware

The board is missing a reset button. S1 is the "flash" button, but it is a bit hard to press. I made the following programming adapter:

A render of the board ...

... but I can't wait that long, so I hand soldered one.

The pin-header on the right-hand-side has the pins a little bent so that it force-fits.

Software

My first goal is to see if we can flash the ESP8266. I felt confident enough to run three tests in one go: serial, led and the three buttons. It is available as arduino sketch.

The pins come form the analyses we did earlier, copying the findings:

• GPIO2 outputs LED D1 (low active)
• GPIO0 inputs switch S1 (low active) also to P1.IO0
• GPIO4 inputs switch S2 (low active)
• GPIO15 inputs switch S3 (high active)

// clocktest.ino - tests the LED and switches on the board
// board: Generic ESP8266 module

#define D1_PIN 2

#define S1_PIN 0
#define S2_PIN 4
#define S3_PIN 15

#define getS1() (digitalRead(S1_PIN)==0) // low active
#define getS2() (digitalRead(S2_PIN)==0) // low active
#define getS3() (digitalRead(S3_PIN)!=0) // high active

void setup() {
  Serial.begin(115200);
  Serial.printf("\n\nclocktest.ino\n\n");

  // configure LEDs (D1)
  digitalWrite(D1_PIN, HIGH); // low active 
  pinMode(D1_PIN, OUTPUT);

  // Configure switches (S1, S2, S3)
  pinMode(S1_PIN, INPUT_PULLUP );
  pinMode(S2_PIN, INPUT_PULLUP );
  pinMode(S3_PIN, INPUT );
}

int count;
void loop() {
  digitalWrite(D1_PIN, LOW); // low active
  delay(200);
  digitalWrite(D1_PIN, HIGH); // low active 
  delay(800); 
  Serial.printf("%04d %d %d %d\n",count++,getS1(),getS2(),getS3());
}

Flash

The development cycle is a bit clumsy.

• Once the source is flashable, press the reset (power interrupt).
• With reset still pressed, press the flash (and keep it pressed).
• Now release the reset but keep flash pressed (this boots the ESP8266 in boot loader mode).
• Now release the flash, the bootloader is now waiting for flash instructions.
• In the Arduino IDE press Upload.
• Once the IDE is done uploading, press and release reset.

With our clocktest app running, the red LED at the back flashes (200ms on, 800ms off). It also print to Serial. I pressed the switches one at a time. This is the output.

clocktest.ino

0000 0 0 0
0001 1 0 0
0002 1 0 0
0003 0 0 0
0004 0 1 0
0005 0 0 0
0006 0 0 0
0007 0 0 1
0008 0 0 1
0009 0 0 0
0010 0 0 0
0011 0 0 0
0012 0 0 0
0013 0 0 0

Display

A very important step is display control. The previous analyses gave us this data

• TM1650 driver for the display
• GPIO13 is "SDA" for TM1650 (not real I2C)
• GPIO12 is "SCL" for TM1650 (not real I2C)

The Arduino comes with two. I picked the lightest one (Sketch > Include library): the 7 segment display driver for TM1650 by Anatoli Arkhipenko. It is also on github.

It appears there is one big issue, the segments are ordered in a funny way, making the built-in font unusable, see disptest.

But I do have full control over all segments, see video.

Note that the decimal point in the center is replaced by the center colon. With the display having 6+6 pins (12), and controlling 4 rows and 8 columns (12), a choice had to be made.

Time keeping chip

Utyf wrote a test application for the DS1302. It relies on a DS103 driver from Erriez.

(end)