ESP32-S3 - Unknown Pins 40-48

[TheoCGaming]

I'm attempting to drive the built-in LCD on the Waveshare ESP32-S3-Touch-LCD-2.8 development board, but the source code that the Waveshare examples use uses pins beyond 39 to drive the LCD. Part of the issue is that I don't know what pin labels 40-48 are supposed to correspond to.

Excerpt of C Header code from ESP32-S3-Touch-LCD-2.8-Demo/ESP-IDF/ESP32-S3-Touch-LCD-2.8-Test/main/LCD_Driver/ST7789.h:

#include "freertos/task.h"
#include "esp_timer.h"
#include "esp_lcd_panel_io.h"
#include "esp_lcd_panel_vendor.h"
#include "esp_lcd_panel_ops.h"
#include "driver/gpio.h"
#include "driver/spi_master.h"
#include "esp_err.h"
#include "esp_log.h"
#include "lvgl.h"
#include "driver/ledc.h"

#include "Vernon_ST7789T.h"
#include "CST328.h"
#include "LVGL_Driver.h"
// LCD SPI GPIO
// Using SPI2 
#define LCD_HOST  SPI3_HOST

#define EXAMPLE_LCD_PIXEL_CLOCK_HZ     (80 * 1000 * 1000)
#define EXAMPLE_LCD_BK_LIGHT_ON_LEVEL  1
#define EXAMPLE_LCD_BK_LIGHT_OFF_LEVEL !EXAMPLE_LCD_BK_LIGHT_ON_LEVEL
#define EXAMPLE_PIN_NUM_MISO           -1
#define EXAMPLE_PIN_NUM_MOSI           45
#define EXAMPLE_PIN_NUM_SCLK           40
#define EXAMPLE_PIN_NUM_LCD_CS         42
#define EXAMPLE_PIN_NUM_LCD_DC         41
#define EXAMPLE_PIN_NUM_LCD_RST        39
#define EXAMPLE_PIN_NUM_BK_LIGHT       5
// The pixel number in horizontal and vertical
#define EXAMPLE_LCD_H_RES              240
#define EXAMPLE_LCD_V_RES              320
// Bit number used to represent command and parameter
#define EXAMPLE_LCD_CMD_BITS           8
#define EXAMPLE_LCD_PARAM_BITS         8

#define Offset_X 0
#define Offset_Y 0

Modified example JS code from ST7789 library:

const LCD_WIDTH = 240;
const LCD_HEIGHT = 320;

// ST7789 demo code on TTGO T-Display
D4.set(); // LCD backlight on
var spi = new SPI();
spi.setup({mosi:45, sck:40});
var g = require("ST7789").connect(spi, 41, 42, 39, function() {
    g.clear();
    g.setRotation(1);
    g.drawString("Hello",0,0);
    g.setFontVector(20);
    g.setColor(0,0.5,1);
    g.drawString("Espruino",0,10);
  });

Espruino console output:

ERROR: pinToESP32Pin: Unknown pin: 40
ERROR: pinToESP32Pin: Unknown pin: 41
ERROR: pinToESP32Pin: Unknown pin: 41
ERROR: pinToESP32Pin: Unknown pin: 42
ERROR: pinToESP32Pin: Unknown pin: 42
ERROR: pinToESP32Pin: Unknown pin: 43
ERROR: pinToESP32Pin: Unknown pin: 43
ERROR: pinToESP32Pin: Unknown pin: 44
ERROR: pinToESP32Pin: Unknown pin: 44
ERROR: pinToESP32Pin: Unknown pin: 45
ERROR: pinToESP32Pin: Unknown pin: 46
ERROR: pinToESP32Pin: Unknown pin: 46
ERROR: pinToESP32Pin: Unknown pin: 47
ERROR: pinToESP32Pin: Unknown pin: 47
ERROR: pinToESP32Pin: Unknown pin: 48
ERROR: pinToESP32Pin: Unknown pin: 48
WARNING: Not removing services for reset() as connected
WARNING: Skip jsble_set_services as connected
 ____                 _
|  __|___ ___ ___ _ _|_|___ ___
|  __|_ -| . |  _| | | |   | . |
|____|___|  _|_| |___|_|_|_|___|
         |_| espruino.com
 2v27 (c) 2025 G.Williams
Espruino is Open Source. Our work is supported
only by sales of official boards and donations:
http://espruino.com/Donate
>
ERROR: pinToESP32Pin: Unknown pin: 40
ERROR: pinToESP32Pin: Unknown pin: 45
Uncaught Error: Function "reset" not found!
    at g (:1:3)
c.reset();a.write(b,f);void 0!==e&&(c.set(),a.write(e,f))
  ^
    at :1:5
g(17);setTimeout(function(){d.forEach(function(b){g(b[0],b[1...
    ^
>

[TheoCGaming]

note: i don't even know if the example code i'm using works properly, it likely doesn't.

[SimonGAndrews]

It looks like the function gpio_num_t pinToESP32Pin in esp32/jshardwate.c is hardcoded checking the pin count for the original ESP32 device only and not the newer ESP32 devices. It is currently

/**
 * Convert an Espruino pin id to a native ESP32 pin id.
 */
gpio_num_t pinToESP32Pin(Pin pin) {
  if ( pin < 40 )
    return pin + GPIO_NUM_0;
  jsError( "pinToESP32Pin: Unknown pin: %d", pin);
  return -1;
}

[SimonGAndrews]

Im happy to test on ESP32, C3 and S3, if a change is cut in.

[SimonGAndrews]

@gfwilliams if you could suggest the best way to dynamically check a valid pin using pinInfo , I will test and generate a patch

Should we call this in jspin.c

bool jshIsPinValid(Pin pin) {
  // Note, PIN_UNDEFINED is always > JSH_PIN_COUNT
  return pin < JSH_PIN_COUNT && (pinInfo[pin].port&JSH_PORT_MASK) != JSH_PORT_NONE;
}

[SimonGAndrews]

so

#include "jspin.h" // for jshIsPinValid()

gpio_num_t pinToESP32Pin(Pin pin) {
  if (jshIsPinValid(pin)) {
    return pin + GPIO_NUM_0;
  }

  jsError("pinToESP32Pin: Invalid or undefined pin: %d", pin);
  return -1;
}

[gfwilliams]

Thanks for looking into this - jshIsPinValid should be the one. If that returns true for a Pin, it is valid,

Is there more than GPIO_NUM_0 for ESP32S3?

If so, in pinInfo we have JSH_PORT_* which are supposed to be for each GPIO port so you could do GPIO_NUM_0 for JSH_PORTD, GPIO_NUM_1 for E, etc.

Also usually you'd also do:

gpio_num_t pinToESP32Pin(Pin pin) {
  if (jshIsPinValid(pin)) {
    return pinInfo[pin].pin + GPIO_NUM_0;
  }

  jsError("pinToESP32Pin: Invalid or undefined pin: %d", pin);
  return -1;
}

It allows people to create builds where the actual pin number on the board doesn't match the CPU's pin number (eg the board manufacturer maybe chose to rename pins)

[TheoCGaming]

return pinInfo[pin].pin + GPIO_NUM_0;

does this mean that I could address raw pin numbers through (theoretically) GPIO_NUM_0 through GPIO_NUM_48, excluding some in the 20s?

[SimonGAndrews]

Hi, there is a fix required to address the pins 40 and above. This will take a couple of days to sort. Maybe Monday. Then all the pins can be referenced in Espruino JavaScript code using D1, D2 , D40, D48 etc. I will test and share working examples.

[TheoCGaming]

any updates?

[SimonGAndrews]

Hi, yes sorry for the delay should get a fix to @gordon in the next couple of days. With the advice above, Its a simple change but there are a few different boards using it to be tested. Im testing with this fix:

/**
 * Convert an Espruino pin id to a native ESP32 pin id.
 */
gpio_num_t pinToESP32Pin(Pin pin) {
  #if ESP_IDF_VERSION_MAJOR >= 4
    // For ESP32-C3, ESP32-S3 and future builds
    if (jshIsPinValid(pin)) {
      return pinInfo[pin].pin + GPIO_NUM_0;
    }
    jsError("pinToESP32Pin: Invalid or undefined pin: %d", pin);
    return -1;
  #else
    // For legacy ESP32 targets, retain original logic to avoid relying on potentially incomplete pinInfo[]
    if (pin < 40)
      return pin + GPIO_NUM_0;
      jsError("pinToESP32Pin: Invalid or undefined pin (<40): %d", pin);
    return -1;
  #endif
  }
  

The original ESP32 would probs also be Ok, but the changes does rely on a valid pin setup in the board.py file and i dont have all the current original targets to test. I will regression test on an ESP32 and test on S3 and C3 with the current board files. The change is building with Github Actions in my Repro for all the boards.

also for testing most of the pin functions wont let the supporting code get as far as the modified pinToESP32Pin() before finding an invalid reference when parsing in the interprter. But the line you are using setting up the spi spi.setup({mosi:45, sck:40}); will trigger the error.

[TheoCGaming]

Tested Simon's fork on commit a4b7c31

The below code appears to work.

// ST7789 demo code on TTGO T-Display
D5.set(); // LCD backlight on
var spi = new SPI();
spi.setup({mosi:D45, sck:D40});
var g = require("ST7789").connect(spi, D41, D42, D39, function() {
    g.clear();
    g.setRotation(1);
    g.drawString("Hello",0,0);
    g.setFontVector(20);
    g.setColor(0,0.5,1);
    g.drawString("Espruino",0,10);
  });

[SimonGAndrews]

Good news, thanks, I’ll test on the other boards before sending a PR to G.