Touch initialization problem

[mark-hoy]

I was attempting to see if the latest tip of tree made any difference in the running size of my binaries, but I ran into a regression with the gt911.py touch initialization. This is with a 7" Crowpanel which uses an ESP32-S3-WROOM-1-N4R8.

7" Crowpanel info

This was working on a Dec 6 2024 build. Mind you, I have not downloaded and rebuilt LVGL-micropython on a regular basis and reflashed the board for all the code updates since then. (I have loaded some of them, but I didn't keep careful track).

LVGL (9.3.0) MicroPython (1.25.0) Binding compiled on 2025-08-04; Generic ESP32S3 module with Octal-SPIRAM with ESP32S3
Type "help()" for more information.
>>> import gui

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "gui.py", line 18, in <module>
  File "crowpanel7_init.py", line 85, in <module>
  File "init_touch.py", line 47, in <module>
  File "gt911.py", line 83, in __init__
  File "gt911.py", line 103, in hw_reset
  File "gt911.py", line 50, in _write_reg
  File "i2c.py", line 123, in write_mem
  File "i2c.py", line 82, in writeto_mem
OSError: [Errno 116] ETIMEDOUT
>>> 

I was having exactly the same problem back in Nov of 2024, but a fix in early Dec 2024 fixed it. I was in discussions with @MitchBradley and he had this to say at the time.

Working with @lytke, we got the gt911 driver working on a rev 3 board. The changes have been pushed up
to the repo. There were two problems. One is that they changed the hardware so you now have to reset the
gt911 chip by turning on a pin on the io expander. The other is that 400khz is too fast fro the i2c bus on some
boards, so the frequency is now at 100000.

Which I verified with clone, build and test with a working build on Dec 6, 2024.

[kdschlosser]

ok so both of those issues are not with the driver but instead what parameters you are passing to the driver. The user is responsible for creating the the SPI bus instance and the device instance which is where the frequency is set. the reset pin I have updated the code in the driver so you can pass an instance of the Pin class for an io_expander to the driver and it will be abelt to turn the pin on and off like any other pin. So still not an issue with the driver but instead it would be because of the user not passing the io_expander pin instance to the driver.

[mark-hoy]

Since I never did either of those things, it's weird that I ever got a working build back in December. I'm guessing a timing issue and I got lucky with a build?

[mark-hoy]

Whoops. I looked more carefully at the init_touch.py code I am using and indeed it is trying to do that... this part hasn't changed since December either. (I mis-remembered where the fix was put in). Anyway, tired and will sleep on it.

def reset_tp():
    pca = pca9557.PCA9557(I2C_BUS, 0x18)
    pca.setPolarity(0)    # All active high
    pca.setDirection(0)   # All out
    pca.output(0)  # All pins low
    time.sleep_ms(20)
    pca.output(1)  # Set IO0 high
    time.sleep_ms(100)
    pca.setDirection(2)  # IO1 in


try:
    reset_tp()
except:
    pass

TOUCH_DEVICE = I2C.Device(
    I2C_BUS,
    dev_id=gt911.I2C_ADDR,
    reg_bits=gt911.BITS
)

[kdschlosser]

I am not sure why it was working and then it stopped working.

Over the past few weeks I have been working on rewriting the I2C in MicroPython so it is more like the SPI I wrote a while back. The version I am writing also uses the new I2C API in the ESP-IDF so that may be where the issue is. It could be a problem in the legacy API that came up with the last ESP-IDF version upgrade I did earlier this year.

I have also modified the SPI as well and added some additional methods that work like some of the methods in the I2C.

What was nice about the I2C driver design is it has 2 methods that are specifically used for sending to the memory registers on a device. those methods are readfrom_mem and writeto_mem. I added methods to the SPI that have the same API and allow for passing the memory address being written to as a separate parameter than the data being sent. This will make for a more seamless integration into driver code like the touch drivers. Touch IC's are very much like display IC's where a single IC is capable of being run on either I2C or SPI, it just depends on how it is connected to the MCU. When setting things or collecting data from the IC the same memory registers are used but because of how MicroPython had the I2C and the SPI drivers written writing a single driver to handle that specific IC needed to have a lot of additional code to check what kind of connection was made. I had mitigated some of that by writing a wrapper around the MicroPython I2C but it was clunky and I really didn't care for it. Having identical methods between I2C and SPI is going to make it easier to add touch, io expander and imu drivers.

[mark-hoy]

I added a bunch more print statements and see the exception on the setDirection(). This is occurring fairly early in touch setup and is likely a causing other issues down the line.

Perhaps I should re-write the pca9557.py to more closely follow your new methods. Is there a particular IO Expander example that would be best to follow or are all of them up to date with the new coding methods?

LVGL (9.2.2) MicroPython (1.24.1) Binding compiled on 2025-08-05; Generic ESP32S3 module with Octal-SPIRAM with ESP32S3
Type "help()" for more information.
>>> import init_touch
init_touch start
call reset_tp()
inside reset_tp()
PCA9557 __init__: <Bus object at 3c254f00>  address: 24
return PCA9557 __init__
pca setPolarity(0)
in setPolarity
exception in reset_tp(): [Errno 116] ETIMEDOUT
running new init_touch.py code
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "init_touch.py", line 59, in <module>
  File "gt911.py", line 83, in __init__
  File "gt911.py", line 103, in hw_reset
  File "gt911.py", line 50, in _write_reg
  File "i2c.py", line 123, in write_mem
  File "i2c.py", line 82, in writeto_mem
OSError: [Errno 116] ETIMEDOUT
>>> 

$ less pca9557.py
"""Driver for PCA9557 I2C I/O Expander"""

REG_INP = 0
REG_OUT = 1   # Default: 0x00                                                                                                                                                 
REG_INV = 2   # Invert input pins. Defaults to 0xF0                                                                                                                           
REG_DIR = 3   # Direction: 1=In, 0=Out. Defaults to 0xFF                                                                                                                      


class PCA9557():
    """I2C I/O Expander Driver"""

    def __init__(self, i2c, address):
        print("PCA9557 __init__:", i2c, " address:", address)
        self.i2c = i2c
        self.addr = address
	self.resultbuf = bytearray(1)
        self.cached_out = 0
	print("return PCA9557 __init__")

    def setDirection(self, val):
        """Set direction register"""
        print("in setDirection")
        self.write(REG_DIR, val)
        print("in setDirection after write")

$ less init_touch.py
from i2c import I2C
import gt911

I2C_BUS = I2C.Bus(
    host=1,
    scl=20,
    sda=19,
    freq=100000,
    use_locks=False
)

# Version 3 boards have a PCA9557 IO Expander chip to reset                                                                                                                   
# the touch panel.                                                                                                                                                            
import pca9557
import time

print("init_touch start")

def reset_tp():
    print("inside reset_tp()")
    pca = pca9557.PCA9557(I2C_BUS, 0x18)
    print("pca setPolarity(0)")
    pca.setPolarity(0)    # All active high                                                                                                                                   
    print("pca setDirection(0)")
    pca.setDirection(0)   # All out                                                                                                                                           
    print("pca output(0)")
    pca.output(0)  # All pins low                                                                                                                                             
    print("before sleep")
    time.sleep_ms(30)
    print("after 1st sleep")
    pca.output(1)  # Set IO0 high                                                                                                                                             
    print("before sleep")
    time.sleep_ms(140)
    print("after 2st sleep")
    pca.setDirection(2)  # IO1 in                                                                                                                                             


try:
    print("call reset_tp()")
    reset_tp()
    print("back from reset_tp()")
except Exception as e:
    print("exception in reset_tp():", e)
    pass