ESP32 I2C PCF8574 read issue

[Gustavomurta]

In February 2018, I ran my sketch (arduino IDE) in my project - ESP32 digital voltmeter and it worked fine - Arduino IDE 1.8.5 and ESP32 Board version 1.0.0.
The communication of the digital voltmeter is made with PCF8574 I2C interface.
Pullups resistors are 3K3 ohms (VCC = 3.3V)

Links of my project:
https://www.elektormagazine.com/labs/esp32-digital-voltmeter#/comments/labs/1459
https://github.com/Gustavomurta/ESP32-DVM

Schematic of ESP32 Voltmeter
https://github.com/Gustavomurta/ESP32-DVM/blob/master/ESP32%20DVM7135%20V3.jpg

Hardware:

Board: DOIT ESP32 DEVKIT V1
Core Installation version: 1.0.2
IDE name: Arduino IDE 1.8.9
Flash Frequency: 80 MHz
PSRAM enabled: NO
Upload Speed: 115200
Computer OS: Windows 10

The sketch I use to read ESP32 voltmeter is:
https://github.com/Gustavomurta/ESP32-DVM/blob/master/ESP32_DVM7135_PT_V1.ino

Simple as -
`

void ReadData ()

{

 Wire.begin();                   // Start I2C

 Wire.requestFrom(PCF8574, 1);   // Read One Byte from PCF8574

 pcfData = Wire.read();          // Byte Read

}

`

Now with Arduino 1.8.9 and ESP32 Board version 1.0.2, the I2C interface runs in crazy mode. The SCL pin sends continuous pulses and the SDA returns with erroneous data (checked with logic analyzer).
My ESP32 is DOIT ESP32 DevKit V1 and the all hardware is OK and checked with my I2C scanner. (based on Nick Gammon).

https://github.com/Gustavomurta/ESP32-DVM/blob/1bc07438e89eac39ae83f6d824451ad7248b3536/ESP32_I2Cscanner2.ino

Messages at Arduino Serial Console:

configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:928
ho 0 tail 12 room 4
load:0x40078000,len:8424
ho 0 tail 12 room 4
load:0x40080400,len:5868
entry 0x4008069c

I2C scanner. Scanning ...
Found address: 32 (0x20)
Found 1 device(s).

Researching this problem with the Debug option, I found these messages.
But I have not identified the error yet. No error is being detected.
I suspect there is now a conflict between I2C and PWM Channel 0 that I use to generate clock of 480 KHz to TLC 7135 (Voltmeter chip). Note that my project worked fine with old libraries.

rst:0x1 (POWERON_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:928
ho 0 tail 12 room 4
load:0x40078000,len:8424
ho 0 tail 12 room 4
load:0x40080400,len:5868
entry 0x4008069c
[D][esp32-hal-i2c.c:1337] i2cProcQueue():  Busy Timeout start=0xd6, end=0xd6, =0, max=50 error=0
[E][esp32-hal-i2c.c:319] i2cDumpI2c(): i2c=0x3ffbebe0
[I][esp32-hal-i2c.c:320] i2cDumpI2c(): dev=0x60013000 date=0x16042000
[I][esp32-hal-i2c.c:322] i2cDumpI2c(): lock=0x3ffb84ec
[I][esp32-hal-i2c.c:324] i2cDumpI2c(): num=0
[I][esp32-hal-i2c.c:325] i2cDumpI2c(): mode=1
[I][esp32-hal-i2c.c:326] i2cDumpI2c(): stage=3
[I][esp32-hal-i2c.c:327] i2cDumpI2c(): error=0
[I][esp32-hal-i2c.c:328] i2cDumpI2c(): event=0x3ffb8570 bits=0
[I][esp32-hal-i2c.c:329] i2cDumpI2c(): intr_handle=0x3ffb85a0
[I][esp32-hal-i2c.c:330] i2cDumpI2c(): dq=0x3ffb854c
[I][esp32-hal-i2c.c:331] i2cDumpI2c(): queueCount=1
[I][esp32-hal-i2c.c:332] i2cDumpI2c(): queuePos=0
[I][esp32-hal-i2c.c:333] i2cDumpI2c(): errorByteCnt=0
[I][esp32-hal-i2c.c:334] i2cDumpI2c(): errorQueue=0
[I][esp32-hal-i2c.c:335] i2cDumpI2c(): debugFlags=0x00020000
[I][esp32-hal-i2c.c:289] i2cDumpDqData(): [0] 7bit 20 R STOP buf@=0x3ffbfeb8, len=1, pos=0, ctrl=11110
[I][esp32-hal-i2c.c:307] i2cDumpDqData(): 0x0000: .                                00 
[I][esp32-hal-i2c.c:347] i2cDumpInts(): 0 row	count	INTR	TX	RX	Tick 
[I][esp32-hal-i2c.c:438] i2cTriggerDumps(): after ProcQueue
[I][esp32-hal-i2c.c:347] i2cDumpInts(): 0 row	count	INTR	TX	RX	Tick 

The same topic at ESP32 forum:
https://www.esp32.com/viewtopic.php?f=19&t=11261#p45725

Can someone help me? Thanks in advance.

[atanisoft]

@stickbreaker

[Gustavomurta]

Logic analyzer diagram with old libraries- works fine (feb/2018)
https://github.com/Gustavomurta/ESP32-DVM/blob/master/ESP32_DVM7135_data01.JPG

Now I2C runs in wrong mode. The SCL pin sends continuous pulses and the SDA returns with erroneous data.
https://github.com/Gustavomurta/ESP32-DVM/blob/master/ESP32_DVM7135_bug%20at%20I2C.JPG

[Gustavomurta]

Correcting important information!

I was able to do some ESP32 Voltmeter tests on my Laptop.
The Arduino IDE version is 1.8.5 and the CORE version 1.0.0.
The symptom is different, but it does not work either! Only now, Over Voltage does not appear.
The I2C interface still has a problem.

I remembered that the first version of Core I used was the previous version of 1.0.0.
And I used the old method to install the package:
Old method for installing ESP32 in the Arduino IDE:
https://github.com/espressif/arduino-esp32/blob/master/docs/arduino-ide/windows.md

I will try to recreate the environment I used when the project worked well.

[atanisoft]

@Gustavomurta many of the LCD libraries use this same chip IIRC. I haven't seen any problems with LCDs on ant version of arduino-esp32. I suspect it is a bug in the PCF8574 library you are using.

[stickbreaker]

This is the error message. It is saying the I2C bus was not in an idle state when it attempted to use it. The Busy signal is generated when the I2C peripheral see activity on the i2c bus.

[D][esp32-hal-i2c.c:1337] i2cProcQueue(): Busy Timeout start=0xd6, end=0xd6, =0, max=50 error=0

try reporting the errors.

void ReadData (){

  if( Wire.begin()){                   // Start I2C
    uint8_t count =Wire.requestFrom(PCF8574, 1);   // Read One Byte from PCF8574
    if(count ==1 ) {
       pcfData = Wire.read();          // Byte Read
    }
    else {
      Serial.printf(" Wire.requestFrom() failed=%d(%s)\n",Wire.lastError(),Wire.getErrorText(Wire.lastError());
    }
  }
  else {
    Serial.printf(" Wire.begin() failed\n");  
  }
}

Chuck.

[Gustavomurta]

Hi Atanisoft,
I´m not using PCF8574 Library . Only wire library.
#include <Wire.h>

[stickbreaker]

Verify your pins, Wire.begin() without specifying pins uses the defaults defined in the selected board's pins_arduino.h file.

Chuck.

[Gustavomurta]

Verify your pins, Wire.begin() without specifying pins uses the defaults defined in the selected board's pins_arduino.h file.

Chuck.

In my Sketch

# define SDApin 21     // PCF8574 SDA pin15       => GPIO_21
# define SCLpin 22     // PCF8574 SCL pin14       => GPIO_22
# define PCF8574 0x20  // PCF8574 Address

Serial.begin(115200);
  attachInterrupt(digitalPinToInterrupt(STB), TestData, FALLING); // External Interrupt GPIO_4
  Wire.begin (SDApin, SCLpin);           // sda= GPIO_21 /scl= GPIO_22

void ReadData ()
{
  Wire.begin();                   // Start I2C
  Wire.requestFrom(PCF8574, 1);   // Read One Byte from PCF8574
  pcfData = Wire.read();          // Byte Read
}

[stickbreaker]

put the error test in and see what is returned.

Chuck.

[stickbreaker]

Why do you code a Wire.begin() in the read code? It is only needed at boot to configure hardware, or after a bus failure. Wire.begin() Is used to recover from a hung bus. Change your read code to this:

void ReadData (){
   uint8_t count =Wire.requestFrom(PCF8574, 1);   // Read One Byte from PCF8574
    if(count ==1 ) {
       pcfData = Wire.read();          // Byte Read
    }
    else {
      Serial.printf(" Wire.requestFrom() failed=%d(%s)\n",Wire.lastError(),Wire.getErrorText(Wire.lastError());
    }
}

if during the Wire.begin() it senses a hung bus, the recovery procedure is to produce upto 9 clock cycles on SCL while monitoring SDA as soon as SDA goes high the recovery procedure ends.

Chuck.

[Gustavomurta]

This is the error message. It is saying the I2C bus was not in an idle state when it attempted to use it. The Busy signal is generated when the I2C peripheral see activity on the i2c bus.

[D][esp32-hal-i2c.c:1337] i2cProcQueue(): Busy Timeout start=0xd6, end=0xd6, =0, max=50 error=0

try reporting the errors.

void ReadData (){

  if( Wire.begin()){                   // Start I2C
    uint8_t count =Wire.requestFrom(PCF8574, 1);   // Read One Byte from PCF8574
    if(count ==1 ) {
       pcfData = Wire.read();          // Byte Read
    }
    else {
      Serial.printf(" Wire.requestFrom() failed=%d(%s)\n",Wire.lastError(),Wire.getErrorText(Wire.lastError());
    }
  }
  else {
    Serial.printf(" Wire.begin() failed\n");  
  }
}

Chuck.

ESP32_DVM7135_Chuck:76:113: error: expected ')' before ';' token

       Serial.printf(" Wire.requestFrom() failed=%d(%s)\n", Wire.lastError(), Wire.getErrorText(Wire.lastError());

[Gustavomurta]

void ReadData (){
   uint8_t count =Wire.requestFrom(PCF8574, 1);   // Read One Byte from PCF8574
    if(count ==1 ) {
       pcfData = Wire.read();          // Byte Read
    }
    else {
      Serial.printf(" Wire.requestFrom() failed=%d(%s)\n",Wire.lastError(),Wire.getErrorText(Wire.lastError());
    }
}

What is wrong with this line ?
Serial.printf(" Wire.requestFrom() failed=%d(%s)\n", Wire.lastError(), Wire.getErrorText(Wire.lastError());

[Gustavomurta]

I corrected that !

[stickbreaker]

Add another ')' before the semicolon, my mistake.

[stickbreaker]

drop the extra Wire.begin() from the read function.