[SOLVED] Unhandled exception(?) when using 20x4 display, component lcd_pcf8574, relay board

fagzal · September 27, 2022, 11:34pm

I’m trying to set up a 20x4 character display (2004-A) with a built-in 8574T I2C on a 4 relay 8266 board. However, when/if I set up its address (0x27), the device gets into something that looks like a boot loop - becomes unresponsive, and have to be reset and reprogrammed to work again.

The relevant part of the config is:

esphome:
  name: relayboard
  platform: ESP8266
  board: esp12e

i2c:
  sda: 4
  scl: 5
  id: i2c0
  scan: true

display:
  - platform: lcd_pcf8574
    dimensions: 20x4
    i2c_id: i2c0
    update_interval: 30s
    id: mydisplay

If I run this like this, the device boots, connects to the wifi, all is well, but cannot communicate with the display as the address is 0x3F (default), which is wrong:

[01:01:52][I][i2c.arduino:054]: Results from i2c bus scan:
[01:01:52][I][i2c.arduino:060]: Found i2c device at address 0x27
[01:01:52][C][lcd_pcf8574:024]: PCF8574 LCD Display:
[01:01:52][C][lcd_pcf8574:025]:   Columns: 20, Rows: 4
[01:01:52][C][lcd_pcf8574:026]:   Address: 0x3F
[01:01:52][C][lcd_pcf8574:027]:   Update Interval: 1.0s
[01:01:52][E][lcd_pcf8574:029]: Communication with LCD Display failed!

If I set up the correct address (0x27), after running the programming, the board becomes unresponsive.
I could get the following log:

[00:54:51]User exception (panic/abort/assert)
[00:54:51]--------------- CUT HERE FOR EXCEPTION DECODER ---------------
[00:54:51]
[00:54:51]Abort called
[00:54:51]
[00:54:51]>>>stack>>>
WARNING Found stack trace! Trying to decode it
[00:54:51]
[00:54:51]ctx: cont
[00:54:51]sp: 3ffffd90 end: 3fffffc0 offset: 0000
[00:54:51]3ffffd90:  00000000 00000000 00000000 00000000  
[00:54:51]3ffffda0:  000000fe 00000000 00000000 00000000  
[00:54:51]3ffffdb0:  00000000 00000000 00000000 00000020  
[00:54:51]3ffffdc0:  00000014 4020cc58 4fdf3b64 3fff0544  
WARNING Decoded 0x4020cc58: esphome::Scheduler::SchedulerItem::cmp(std::unique_ptr<esphome::Scheduler::SchedulerItem, std::default_delete<esphome::Scheduler::SchedulerItem> > const&, std::unique_ptr<esphome::Scheduler::SchedulerItem, std::default_delete<esphome::Scheduler::SchedulerItem> > const&)
[00:54:51]3ffffdd0:  00000000 3ffeebb4 3fff0454 40215a32  
WARNING Decoded 0x40215a32: raise_exception at core_esp8266_postmortem.cpp
[00:54:51]3ffffde0:  00000000 3fff0400 40100809 40215a44  
WARNING Decoded 0x40100809: millis
WARNING Decoded 0x40215a44: __unhandled_exception
[00:54:51]3ffffdf0:  000000b3 3fff03f4 3fff02e4 40220280  
WARNING Decoded 0x40220280: __gnu_cxx::__throw_insufficient_space(char const*, char const*) at /workdir/repo/gcc-gnu/libstdc++-v3/src/c++11/snprintf_lite.cc:50
[00:54:51]3ffffe00:  3fff0584 3ffeebb4 3fff0588 40205af1  
WARNING Decoded 0x40205af1: esphome::lcd_pcf8574::PCF8574LCDDisplay::call_writer()
[00:54:51]3ffffe10:  00000000 3fff0454 3ffffe50 402059cd  
WARNING Decoded 0x402059cd: esphome::lcd_base::LCDDisplay::update()
[00:54:51]3ffffe20:  00000000 3ffeebb4 3fff0584 4021841a  
WARNING Decoded 0x4021841a: std::_Function_handler<void (), esphome::PollingComponent::call_setup()::{lambda()#1}>::_M_invoke(std::_Any_data const&) at component.cpp
[00:54:51]3ffffe30:  00000000 3ffeebb4 3fff0584 4020d461  
WARNING Decoded 0x4020d461: esphome::Scheduler::call()
[00:54:51]3ffffe40:  0000001e 0000001e 3ffe85e4 40100d83  
WARNING Decoded 0x40100d83: umm_free_core at umm_malloc.cpp
[00:54:51]3ffffe50:  000000b3 3fff0454 3fff03ec 00000000  
[00:54:51]3ffffe60:  3fff0144 00000020 3ffef964 40100f62  
WARNING Decoded 0x40100f62: free
[00:54:51]3ffffe70:  000000b3 00000004 fffeecc2 40220cc0  
WARNING Decoded 0x40220cc0: operator delete(void*) at /workdir/repo/gcc-gnu/libstdc++-v3/libsupc++/del_op.cc:50
[00:54:51]3ffffe80:  3fff0408 3ffffea0 00000005 00000100  
[00:54:51]3ffffe90:  3fff0144 00000004 3ffeebb4 4020c4ad  
WARNING Decoded 0x4020c4ad: esphome::Application::setup()
[00:54:51]3ffffea0:  00000005 00000005 3ffef964 00000000  
[00:54:51]3ffffeb0:  00000014 3ffef964 00000020 4020b402  
WARNING Decoded 0x4020b402: esphome::Application::register_component_(esphome::Component*)
[00:54:51]3ffffec0:  3fff0454 3ffeec58 00000050 3ffeec4c  
[00:54:51]3ffffed0:  3ffeec54 3fff0454 3ffeebb4 4020dac7  
WARNING Decoded 0x4020dac7: setup
[00:54:51]3ffffee0:  01a8c001 01a8c0a6 ffffff01 00000000  
[00:54:51]3ffffef0:  00000000 feefef00 feefeffe feefeffe  
[00:54:51]3fffff00:  3fffff08 00000007 7a646f42 00473261  
[00:54:51]3fffff10:  36312e31 feef0036 feefef00 00000000  
[00:54:51]3fffff20:  3fffff28 00000008 6963616d 6963616c  
[00:54:51]3fffff30:  00000000 00000000 00000000 00000000  
[00:54:51]3fffff40:  01a8c001 01a8c0a6 ffffff01 00000000  
[00:54:51]3fffff50:  00000000 00000000 3fffff60 00000000 <
[00:54:51]3fffff60:  ffffff00 00000000 00000000 feefef00  
[00:54:51]3fffff70:  feefeffe feefeffe feefeffe feefeffe  
[00:54:51]3fffff80:  3fff038c 00000001 feefeffe feefeffe  
[00:54:51]3fffff90:  feefeffe feefeffe feefeffe 3ffef058  
[00:54:51]3fffffa0:  3fffdad0 00000000 3ffef044 4021556c  
WARNING Decoded 0x4021556c: loop_wrapper() at core_esp8266_main.cpp
[00:54:51]3fffffb0:  feefeffe feefeffe 3ffe85e0 401003f1  
WARNING Decoded 0x401003f1: cont_wrapper
[00:54:51]<<<stack<<<

I think this part is relevant:

WARNING Decoded 0x40220280: __gnu_cxx::__throw_insufficient_space(char const*, char const*) at /workdir/repo/gcc-gnu/libstdc+±v3/src/c++11/snprintf_lite.cc:50
WARNING Decoded 0x40205af1: esphome::lcd_pcf8574::PCF8574LCDDisplay::call_writer()
WARNING Decoded 0x402059cd: esphome::lcd_base::LCDDisplay::update()

Looks like an exception from the update loop of the display…

Any ideas?

fagzal · September 28, 2022, 12:00pm

Well, turns out it was a bunch of overlapping errors by me

Update interval 1s for the screen conflicts with the WiFi setup; if set to 2s, the wifi comes up
The module on my board is a esp01_1m not esp12e
Initializing of the display takes more time than expected
The potmeter on the board must be turned all the way down to show any characters (probably due to 3.3V VCC instead of 5V)
I also had an error in one of the lambda-s

I leave this topic here for reference

bremby · October 22, 2022, 5:29pm

Hi,

I can’t make mine work, the display turns on; but I can’t get any text

###################################################################################################
#####  I/O expander hub definition
###################################################################################################
mcp23017:
  - id: 'mcp23017_hub'
    address: 0x20
#nodemcu devkit v4.0
i2c:
  sda: 21
  scl: 22
  scan: True
###################################################################################################
# 20x4 LCD config
display:
  - platform: lcd_pcf8574
    dimensions: 20x4
    address: 0x27
    #update_interval: 2s
    lambda: |-
      it.print("Hello World!");


[19:21:51][C][i2c.arduino:038]: I2C Bus:
[19:21:51][C][i2c.arduino:039]:   SDA Pin: GPIO21
[19:21:51][C][i2c.arduino:040]:   SCL Pin: GPIO22
[19:21:51][C][i2c.arduino:041]:   Frequency: 50000 Hz
[19:21:51][C][i2c.arduino:044]:   Recovery: bus successfully recovered
[19:21:51][I][i2c.arduino:054]: Results from i2c bus scan:
[19:21:51][I][i2c.arduino:060]: Found i2c device at address 0x20
[19:21:51][I][i2c.arduino:060]: Found i2c device at address 0x27
[19:21:51][C][mcp23017:028]: MCP23017:
[19:21:53][C][lcd_pcf8574:024]: PCF8574 LCD Display:
[19:21:53][C][lcd_pcf8574:025]:   Columns: 20, Rows: 4
[19:21:53][C][lcd_pcf8574:026]:   Address: 0x27
[19:21:53][C][lcd_pcf8574:027]:   Update Interval: 1.0s

I’m using this one

any idea?

fagzal · October 22, 2022, 8:07pm

The biggest oops in my case was the potentiometer, which I had to turn all the way up.

Here is the relevant part from my .yml file:

display:
  - platform: lcd_pcf8574
    dimensions: 20x4
    i2c_id: i2c0
    update_interval: 5s
    address: 0x27
    id: mydisplay
    lambda: |-
      char str[17];
      time_t currTime = id(my_time).now().timestamp;
      strftime(str, sizeof(str), "%H:%M:%S", localtime(&currTime));

bremby · October 22, 2022, 8:30pm

thank you @fagzal , changing the interval to 5 and turning up/down until I got the desired “intensity” made the magic.
AWSOME

fagzal · October 25, 2022, 12:02pm

I think the update interval can be smaller, like 2s. You might even go down to 1s, if you also increase the I2C frequency, but I did not try that.

bremby · October 30, 2022, 1:01pm

it works!!!

i2c:
  sda: 21
  scl: 22
  scan: True
  frequency: 100kHz

reference

frequency (Optional, float): Set the frequency the I²C bus should operate on. Defaults to 50kHz. Values are 10kHz, 50kHz, 100kHz, 200kHz, … 800kHz

I²C Bus — ESPHome