How to correctly set a GPIO pin high before the I2C and SSD1306 drivers are initialized #69310

zpm1066 · 2024-02-21T20:16:38Z

zpm1066
Feb 21, 2024

Is your feature request related to a problem? Please describe.
The request is how to correctly enable power on I2C STEMMA connector on a range of Adafruit ESP32-S3 boards before any I2C and SSD1306 (ST7789) display driver initialization.

The Adafruit ESP32-S3 boards have on-board I2C STEMMA connector to allow I2C devices to be
connected to it. In addition some of the boards have an on-board ST7789 135x240 TFT display. I'm trying to connect a I2C SSD1306 display and also use the on-board ST7789 display.

Power to both the I2C Stemma connector and the TFT is controlled by raising a GPIO pin high at a regulator. I2C STEMMA SDA and SCK have 10K pull-up resistors.

Under Arduino, the initialization takes care of enabling power to I2C connector before the user's setup().

Describe the solution you'd like
I would like to enable power to the I2C STEMMA connector so that I can utilize both the on-board ST7789 display, as well as an I2C SSD1306 display (or any other I2C sensor) connected to the I2C STEMMA connector.

Describe alternatives you've considered
I've tried to use gpio-hog and also regulator binding controlled via a GPIO.

Here is the gpio-hog devicetree overlays that I used to set a GPIO pin high during initialization,

&gpio0 {
	status = "okay";

	i2c-tft-power {
		gpio-hog;
		gpios = <21 GPIO_ACTIVE_HIGH>;
		output-high;
	};
};

and the regulator binding with GPIO control

reg_tft_power: reg-tft-power {
	compatible = "regulator-fixed";
	regulator-name = "reg-adafruit";
	enable-gpios = <&gpio0 21 GPIO_ACTIVE_HIGH>;
	regulator-boot-on;
};

In my setup, I have a SSD1306 OLED display connected to the I22 STEMMA conenctor.

I’m able to confirm that the power to the display on the I2C STEMMA connector comes on when
I use gpio-hog or the regulator binding. However, the display still doesn’t show anything.

From the “west espressif monitor”, I’ve confirmed that I2C is in a READY state but the
SSD1306 failed to initialize. I do see 3.26V at the display connected via the I2C STEMMA
and the SDA/SCK signals look fine.

I2C is sending commands/data to the display correctly and there are no crashes on the ESP32-S3 and shell works fine.

I suspect that there may be a sequence issue, for example, gpio-hog or regulator binding enabling the I2C power
after SSD1306 but before I2C initialization.

Is there a way to check the order of I2C, SSD1306 and gpio-hog ( or regulator binding) priority in Zephyr?

Is gpio-hog or regulator binding the right way to turn on I2C power on initialization?

Additional context
Alternatively, Should I be using SYS_INIT() with PRE_KERNEL and set the I2C power
GPIO high in early_init() as in the example below?

`SYS_INIT(early_init, PRE_KERNEL_1, 0)`

GeorgeCGV · 2024-02-21T22:00:25Z

GeorgeCGV
Feb 21, 2024
Collaborator

Is there a way to check the order of I2C, SSD1306 and gpio-hog ( or regulator binding) priority in Zephyr?

Since Zephyr 3.5.0 there is west build -t initlevels to print out the init order.

A SYS_INIT is not a bad approach to deal with permanent board init.

0 replies

zpm1066 · 2024-02-21T22:58:37Z

zpm1066
Feb 21, 2024
Author

@GeorgeCGV Thanks.

In using gpio-hog

&gpio0 {
	status = "okay";
	i2c-tft-power {
		gpio-hog;
		gpios = <21 GPIO_ACTIVE_HIGH>;
		output-high;
	};
};

and from the initlevels output below, it looks like a __init_gpio_hogs_init: gpio_hogs_init(NULL)

should set GPIO HIGH correctly init before I2C and SSD1306 gets initialized.

I have verified that I'mgetting 3.26V at the I2C STEMMA connector and SDA/SCK levels look fine. Data is being pushed on to the I2C but SSD1306 is uninitialized.

I'll try using SYS_INIT(early_init, PRE_KERNEL_1, 0)

What is the best way to get the GPIO 21 pin directly when calling from early_init? Thanks.

[00:00:00.228,000] <err> i2c_esp32: I2C transfer error: -14
[00:00:00.228,000] <err> ssd1306: Failed to initialize device!
*** Booting Zephyr OS build zephyr-v3.5.0-4872-gcf14d4f1fd6d ***
[00:00:00.228,000] <inf> main: main_thread
Display device not ready
[00:00:00.228,000] <dbg> cfb: cfb_framebuffer_init: number of fonts 2
[00:00:00.317,000] <inf> display: Index[0] font dimensions  5x8
[00:00:00.317,000] <inf> display: Index[1] font dimensions  8x8
[00:00:00.317,000] <inf> display: Selected font: index[3]
[00:00:00.317,000] <inf> display: x_res 128, y_res 64, ppt 8, rows 8, cols 128
[00:00:00.317,000] <inf> display: Zephyr v3.5.99

[00:00:00.317,000] <inf> display: adafruit_esp32s3_tft_feather
uart:~$ device list
devices:
- rtc@60021000 (READY)
- gpio@60004800 (READY)
- gpio@60004000 (READY)
- trng@6003507c (READY)
- uart@60000000 (READY)
- uart@60038000 (READY)
- i2c@60013000 (READY)
- ssd1306@3c (DISABLED)
uart:~$

Successfully created esp32s3 image.
[409/410] cd /Users/quark11/Documents/2024_zephyr_dev/ssd13...128x64_dht_esp32s3_ref/build/zephyr/zephyr.elf --initlevels
EARLY
PRE_KERNEL_1
  __init___device_dts_ord_32: clock_control_esp32_init(__device_dts_ord_32)
  __init_init_mem_slab_obj_core_list: init_mem_slab_obj_core_list(NULL)
  __init_statics_init_pre: statics_init(NULL)
  __init___device_dts_ord_7: gpio_esp32_init(__device_dts_ord_7)
  __init___device_dts_ord_68: gpio_esp32_init(__device_dts_ord_68)
  __init___device_dts_ord_53: entropy_esp32_init(__device_dts_ord_53)
  __init___device_dts_ord_54: uart_esp32_init(__device_dts_ord_54)
  __init___device_dts_ord_57: serial_esp32_usb_init(__device_dts_ord_57)
  __init_uart_console_init: uart_console_init(NULL)
PRE_KERNEL_2
  __init_sys_clock_driver_init: sys_clock_driver_init(NULL)
POST_KERNEL
  __init_enable_logger: enable_logger(NULL)
  __init_enable_shell_uart: enable_shell_uart(NULL)
  __init_malloc_prepare: malloc_prepare(NULL)
  __init_k_sys_work_q_init: k_sys_work_q_init(NULL)
  __init_gpio_hogs_init: gpio_hogs_init(NULL)
  __init___device_dts_ord_70: i2c_esp32_init(__device_dts_ord_70)
  __init___device_dts_ord_72: ssd1306_init(__device_dts_ord_72)
  __init___device_dts_ord_8: dht_init(__device_dts_ord_8)
APPLICATION
  __init_lvgl_init: lvgl_init(NULL)
SMP

6 replies

zpm1066 Feb 22, 2024
Author

Agreed. The order looks fine.

However, in the Espressif Monitor output, we do see that SSD1306: Failed to initialise device!

The device list confirms that I2C is ready but SSD1306 is disabled. Also, I2C is sending commands correctly and program isn’t crashing. It’s in a loop refreshing the display.

Is there a way to have gpio-hog in PRE KERNEL, so the I2T Power GPIO is set high much earlier?

If not, then I may try using SYS_INIT.

If I use something like SYS_INIT(early_init, PRE_KERNEL_1, 0), What is the best way to get the GPIO 21 pin directly when calling from early_init? How should I define it in the devicetree overlay? I don’t think I can have it under led GPIO section.

[[00:00:00.228,000] i2c_esp32: I2C transfer error: -14
[00:00:00.228,000] ssd1306: Failed to initialize device!
*** Booting Zephyr OS build zephyr-v3.5.0-4872-gcf14d4f1fd6d ***
[00:00:00.228,000] main: main_thread
Display device not ready
[00:00:00.228,000] cfb: cfb_framebuffer_init: number of fonts 2
[00:00:00.317,000] display: Index[0] font dimensions 5x8
[00:00:00.317,000] display: Index[1] font dimensions 8x8
[00:00:00.317,000] display: Selected font: index[3]
[00:00:00.317,000] display: x_res 128, y_res 64, ppt 8, rows 8, cols 128
[00:00:00.317,000] display: Zephyr v3.5.99

[00:00:00.317,000] display: adafruit_esp32s3_tft_feather
uart:~$ device list
devices:

rtc@60021000 (READY)
gpio@60004800 (READY)
gpio@60004000 (READY)
trng@6003507c (READY)
uart@60000000 (READY)
uart@60038000 (READY)
i2c@60013000 (READY)
ssd1306@3c (DISABLED)

GeorgeCGV Feb 22, 2024
Collaborator

Is there a way to have gpio-hog in PRE KERNEL, so the I2T Power GPIO is set high much earlier?

The sda1306 driver allows to set a delay in init using ready-time-ms DT property. It is set to 10 milliseconds by default.

zephyr/drivers/display/ssd1306.c

Line 441 in dc8dff0

k_sleep(K_TIMEOUT_ABS_MS(config->ready_time_ms));

If I use something like SYS_INIT(early_init, PRE_KERNEL_1, 0), What is the best way to get the GPIO 21 pin directly when calling from early_init? How should I define it in the devicetree overlay? I don’t think I can have it under led GPIO section.

It is ok to have it as led for a quick test. The early_init needs to get the gpio dt spec using macros. The blinky sample can be used as example.

zpm1066 Feb 23, 2024
Author

#@GeorgeCGV The SSD1306 connected to the I2C STEMMA connector works! Thank you for your assistance. It's much appreciated.

I had to set ready_time_ms in the ssd1306 overlay to the display to come up.

220 ms is the lowest value worked with the esp32s3_tft_feather and esp32s3_feather boards. I've gone with 250 ms.

&i2c0 {
	pinctrl-names = "default";
	status = "okay";
	clock-frequency = <I2C_BITRATE_STANDARD>;
	ssd1306: ssd1306@3c {
		compatible = "solomon,ssd1306fb";
		reg = <0x3c>;
		width = <128>;
		height = <64>;
		segment-offset = <0>;
		page-offset = <0>;
		display-offset = <0>;
		multiplex-ratio = <63>;
		segment-remap;
		com-invdir;
		prechargep = <0x22>;
		ready-time-ms = < 250 >;
	};
};
 #```

Now, I'm trying to get the ST7789 on the esp32s3_tft_feather to work but seem to be running into a similar issue with ST7789 TFT as I did with SSD1306. I would appreciate if you can suggest what may be happening.

I'm using the following overlay with `gpio-hog` to enable power to the TFT by setting GPIO I2C_TFT_Power high, as before. Also, setting the backlight.

The ST7789 CS, DC, RST and SCK/MOSI are set as per the Adafruit ESP32S3-TFT Feather pinouts.

// I2C_TFT_Power = GPIO21, TFT_Backlight = GPIO45
&gpio0 {
status = "okay";
i2c-tft-power {
gpio-hog;
gpios = <21 GPIO_ACTIVE_HIGH>, <45 GPIO_ACTIVE_HIGH>;
output-high;
};
};

&spi2 {
compatible = "espressif,esp32-spi";
status = "okay";
cs-gpios = <&gpio0 7 GPIO_ACTIVE_LOW>;

st7789v: st7789v@0 {
	compatible = "sitronix,st7789v";
	label = "ST7789V";
	spi-max-frequency = <20000000>;
	reg = <0>;
	cmd-data-gpios = <&gpio0 39 GPIO_ACTIVE_LOW>; 
	reset-gpios = <&gpio0 40 GPIO_ACTIVE_LOW>;     
	width = <135>;
	height = <240>;
	x-offset = <52>;
	y-offset = <40>;
	vcom = <0x19>;
	gctrl = <0x35>;
	vrhs = <0x12>;
	vdvs = <0x20>;
	mdac = <0x00>;
	gamma = <0x01>;
	colmod = <0x05>;
	lcm = <0x2c>;
	porch-param = [0c 0c 00 33 33];
	cmd2en-param = [5a 69 02 01];
	pwctrl1-param = [a4 a1];
	pvgam-param = [D0 04 0D 11 13 2B 3F 54 4C 18 0D 0B 1F 23];
	nvgam-param = [D0 04 0C 11 13 2C 3F 44 51 2F 1F 1F 20 23];
	ram-param = [00 F0];
	rgb-param = [CD 08 14];
};

};


The init order, `gpio_hogs` -> `spi_esp32_init` -> `st7789v_init` looks fine.

PRE_KERNEL_1
__init___device_dts_ord_30: clock_control_esp32_init(__device_dts_ord_30)
__init_init_mem_slab_obj_core_list: init_mem_slab_obj_core_list(NULL)
__init_statics_init_pre: statics_init(NULL)
__init___device_dts_ord_7: gpio_esp32_init(__device_dts_ord_7)
__init___device_dts_ord_65: gpio_esp32_init(__device_dts_ord_65)
__init___device_dts_ord_50: entropy_esp32_init(__device_dts_ord_50)
__init___device_dts_ord_51: uart_esp32_init(__device_dts_ord_51)
__init___device_dts_ord_54: serial_esp32_usb_init(__device_dts_ord_54)
__init_uart_console_init: uart_console_init(NULL)
PRE_KERNEL_2
__init_sys_clock_driver_init: sys_clock_driver_init(NULL)
POST_KERNEL
__init_enable_logger: enable_logger(NULL)
__init_enable_shell_uart: enable_shell_uart(NULL)
__init_malloc_prepare: malloc_prepare(NULL)
__init_k_sys_work_q_init: k_sys_work_q_init(NULL)
__init_gpio_hogs_init: gpio_hogs_init(NULL)
__init___device_dts_ord_70: spi_esp32_init(__device_dts_ord_70)
__init___device_dts_ord_71: st7789v_init(__device_dts_ord_71)
__init___device_dts_ord_8: dht_init(__device_dts_ord_8)
APPLICATION
__init_lvgl_init: lvgl_init(NULL)
SMP


Here is the `Espressif Monitor` output.

*** Booting Zephyr OS build zephyr-v3.5.0-4872-gcf14d4f1fd6d ***
[00:00:00.418,000] app: main
[00:00:00.419,000] app: Zephyr RTOS: 3.5.99

[00:00:00.419,000] app: adafruit_esp32s3_tft_feather
[00:00:00.419,000] app: Initialized ST7789V

uart:~$ device list
devices:

rtc@60021000 (READY)
gpio@60004800 (READY)
gpio@60004000 (READY)
trng@6003507c (READY)
uart@60000000 (READY)
uart@60038000 (READY)
spi@60024000 (READY)
ST7789V (READY)


Both SPI and ST7789 are in a READY state. The firmware is running fine with no errors.

If I switch to using the ST7789 overlay (after modifying the overlay to use different CS, DC, and RST pins) with an external standalone ST7789 TFT connected to the board pins, the ST7789 works without any issues.

I'm not sure what's going on. I feel I'm pretty close to getting the whole ST7789 to work.  

Any thoughts on what may be the issue? Thanks.

GeorgeCGV Feb 24, 2024
Collaborator

Glad that it worked.

As for ST7789 make sure the max frequency is set correctly. Shouldn't it be 8 MHz for that display (DT_FREQ_M(8))? Would be great to validate the existence of SPI data exchange.

Depending on the use case it might be necessary to provide it to zephyr,display.

Options like width, height, and others must be set accordingly.

zpm1066 Feb 25, 2024
Author

#@GeorgeCGV

I tried using 8Mz and also 1 MHz, it didn't make any difference.

I think 20Mhz should be fine, as I have an identical ST7789 135x240 that runs fine when connected to the TFT Feather board pin.
The only change to the overlay was changing pins for CS, DC, and RST. The MOSI and SCK were the same as what the on-board ST7789 uses.

I reviewed spi_esp32_spim.c but didn't see anything that stood out to be changed.

overlay snippet - as before zephyr display is set to st7789v:

 chosen {
		zephyr,display = &st7789v;
	};

and spi2 has the changed cs-gpios, cmd-data-gpios, and reset-gpios for the ST7789 using the Feather board pins.

&spi2 {
	compatible = "espressif,esp32-spi";
	status = "okay";
	cs-gpios = <&gpio0 9 GPIO_ACTIVE_LOW>; 

	st7789v: st7789v@0 {
		compatible = "sitronix,st7789v";
		label = "ST7789V";
		spi-max-frequency = <20000000>;
		reg = <0>;
		cmd-data-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;  
		reset-gpios = <&gpio0 8 GPIO_ACTIVE_LOW>;     
		width = <135>;
		height = <240>;
		x-offset = <52>;
		y-offset = <40>;
		vcom = <0x19>;
		gctrl = <0x35>;
		vrhs = <0x12>;
		vdvs = <0x20>;
		mdac = <0x00>;
		gamma = <0x01>;
		colmod = <0x05>;
		lcm = <0x2c>;
		porch-param = [0c 0c 00 33 33];
		cmd2en-param = [5a 69 02 01];
		pwctrl1-param = [a4 a1];
		pvgam-param = [D0 04 0D 11 13 2B 3F 54 4C 18 0D 0B 1F 23];
		nvgam-param = [D0 04 0C 11 13 2C 3F 44 51 2F 1F 1F 20 23];
		ram-param = [00 F0];
		rgb-param = [CD 08 14];
	};
};

How to correctly set a GPIO pin high before the I2C and SSD1306 drivers are initialized #69310

Uh oh!

zpm1066 Feb 21, 2024

Replies: 2 comments · 6 replies

Uh oh!

GeorgeCGV Feb 21, 2024 Collaborator

Uh oh!

Uh oh!

zpm1066 Feb 21, 2024 Author

Uh oh!

zpm1066 Feb 22, 2024 Author

Uh oh!

GeorgeCGV Feb 22, 2024 Collaborator

Uh oh!

Uh oh!

zpm1066 Feb 23, 2024 Author

Uh oh!

Uh oh!

GeorgeCGV Feb 24, 2024 Collaborator

Uh oh!

Uh oh!

zpm1066 Feb 25, 2024 Author

zpm1066
Feb 21, 2024

Replies: 2 comments 6 replies

GeorgeCGV
Feb 21, 2024
Collaborator

zpm1066
Feb 21, 2024
Author

zpm1066 Feb 22, 2024
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GeorgeCGV Feb 22, 2024
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zpm1066 Feb 23, 2024
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