Should be possible to digitalRead() a pin that's not GPIO

[egnor]

Board

All

Device Description

Any device

Hardware Configuration

Any configuration

Version

latest master (checkout manually)

IDE Name

any IDE

Operating System

any OS

Flash frequency

any frequency

PSRAM enabled

yes

Upload speed

any

Description

in arduino-esp32 3.x, if you attempt to digitalRead() from a pin that's been configured as another peripheral (e.g. I2C or UART), an error message comes back like

[4629150][E][esp32-hal-gpio.c:190] __digitalRead(): IO 16 is not set as GPIO.

and the function always returns 0. in previous versions it was possible to see the state of the pin regardless of what peripheral is driving it (which is perfectly well supported by hardware). there are a number of use cases for this, for monitoring what a peripheral is actually doing, for seeing if something externally is overriding it, etc..

the code in question is here:

arduino-esp32/cores/esp32/esp32-hal-gpio.c

Line 187 in 7018cd1

if (perimanGetPinBus(pin, ESP32_BUS_TYPE_GPIO) != NULL) {

(as far as I know, gpio_get_level() will always work even if the pin is driven by another peripheral, so I think the check can just be skipped?) if the change is intentional, it should probably be put in the migration document??

Sketch

void setup() {
  Serial.begin(115200);
  I2C.begin();
}

void loop() {
  delay(500);
  Serial.println(digitalRead(SDA));
}

Debug Message

[5220153][E][esp32-hal-gpio.c:190] __digitalRead(): IO 16 is not set as GPIO.

(actual pin number may vary of course)

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[P-R-O-C-H-Y]

Hi @egnor, can you please give it a test without the check if (perimanGetPinBus(pin, ESP32_BUS_TYPE_GPIO) != NULL) {
if it works as you expect? There is also this note in gpio.h file in IDF for gpio_get_level():
@warning If the pad is not configured for input (or input and output) the returned value is always 0.

So this may work for some pins of peripherals, but may not for everything.

PS: Thanks for very nice report.

[vvb333007]

Similar issue with pinMode():
I am trying to set OUTPUT ENABLE on a reserved pin 6 (used internally for SPI) on my ESP32 Devkit. If I do it with IDF functions then it is all fine. But if I call pinMode() then it all goes through periman, causing pin deinit function to be called, pin getting reconfigured eventually leading to system crash and reboot. Yes I understand that I am doing dangerous stuff, but IDF allows for it so why pinMode() doesn't.. But as I can understand it all requires a massive periman logic change :(

[P-R-O-C-H-Y]

@vvb333007 What is the point of setting OUTPUT ENABLE on internally used pin for SPI (just curious)?
You can always you Arduino as a IDF component if you need to do something specific or more detailed stuff.
The Permian is working really well of handling pins between peripherals. With logic of peripheral manager you can use same pin for multiple peripherals at the same time.

Did you have any time to properly test the gpio_get_level() as I asked in previous comment?

[vvb333007]

Yes it works if periman call is commented.

I am just thinking that pinMode() must not call deinit when I just want to add 1 more flag, and do not reconfigure pin to GPIO funxtion.

If I am manipulating flags on live UART TX pin for example I want that pin to remain UART TX, not switch to GPIO.
Currently I use IDF functions for that, so it is not a big deal.

As I see it that digitalWrite() is the function which must check the bus type and reconfigure pin to GPIO function on attempt to set digital value.

Did you have any time to properly test the gpio_get_level() as I asked in previous comment?

[vvb333007]

@vvb333007 What is the point of setting OUTPUT ENABLE on internally used pin for SPI (just curious)?

I am making a shell (a devel/debug tool) which among other things provides commands for pin manipulation. While I was
playing with it I suddenly discovered that pinMode(6, OUTPUT|INPUT|PULL_UP) causes system crash.

I know that pin 6 is used internally for the memory access but still.. It is just only 1 flag was updated, other flags remain unchanged and it crashed. I looked into it and found that idf functions alone do not crash the whole sketch. Then I found this bug report and thats why I posted it here.

Thats the full story.

[vvb333007]

Did you have any time to properly test the gpio_get_level() as I asked in previous comment?

Another thing to consider:

By default, many pins of ESP32 are routed through IO MUX and have function of GPIO. Such pins are ready to be used, however
Periman marks them as being in INIT state. As result digitalRead() or digitalWrite() are not working. If, however, I call pinMode(.., INPUT), then pin gets reconfigured: now it is routed through GPIO Matrix and have a function of "simple GPIO input".

As such you are not able to digitalRead() interface pin (uart for example): it is either not readable because of what is said in the very first message, or it loses its IOMUX function (being uart_tx for example) because of pinMode(...).

But yes as you just said anyone can simply use IDF function in their Arduino sketch to do such a specific stuff.

Just a thought.
May be Periman should not mark GPIO pins as INIT if they are already configured as "GPIO" via IO_MUX?

[SinekaRamu]

Hi @P-R-O-C-H-Y, Issue with Using SD Card GPIO Pins on ESP32-CAM

I am working with the ESP32-CAM and trying to use GPIO pins that are normally allocated for the SD card (e.g., GPIOs 2, 4, 12, 13, 14, 15) as general-purpose GPIOs. However, I am not using an SD card in my project and have ensured that the SD card functionality is not initialized in my code.

Despite this, I encounter the following error:
[ 979][E][esp32-hal-gpio.c:190] __digitalRead(): IO 15 is not set as GPIO.

Is there a way to configure or free up these GPIO pins for general-purpose use on the ESP32-CAM?

Thanks in advance for your help!

[P-R-O-C-H-Y]

Hi @P-R-O-C-H-Y, Issue with Using SD Card GPIO Pins on ESP32-CAM

I am working with the ESP32-CAM and trying to use GPIO pins that are normally allocated for the SD card (e.g., GPIOs 2, 4, 12, 13, 14, 15) as general-purpose GPIOs. However, I am not using an SD card in my project and have ensured that the SD card functionality is not initialized in my code.

Despite this, I encounter the following error: [ 979][E][esp32-hal-gpio.c:190] __digitalRead(): IO 15 is not set as GPIO.

Is there a way to configure or free up these GPIO pins for general-purpose use on the ESP32-CAM?

Thanks in advance for your help!

Hi @SinekaRamu, first you need to call a pinMode() function to set it as a GPIO pin. Check the docs here.

[SinekaRamu]

Hi @SinekaRamu, first you need to call a pinMode() function to set it as a GPIO pin. Check the docs here.

pinmode for OUTPUT is working fine, While defining a input pin it gives wired output

`
void setup() {
Serial.begin(115200);
pinMode(2, INPUT);
}

void loop() {
Serial.println("testing"+ digitalRead(2));
delay(1000);
}
`
while OFF = testing
while ON = esting
I did get the value like 0 or 1.