ULP ADC read fails

[ayavilevich]

Board

ESP32 generic dev module

Device Description

ESP32 generic dev module. Nothing additional connected.

Hardware Configuration

Nothing additional connected.

Version

latest stable Release (if not listed below)

IDE Name

Arduino IDE 2.3.6 and Platform.IO on VSC

Operating System

Windows 10

Flash frequency

40MHz

PSRAM enabled

no

Upload speed

921600

Description

Since Arduino-ESP32 2.0.14, using an ADC read operation in ESP32 ULP FSM co processor will cause the ULP to get "stuck".

I am including minimal code to reproduce.

Expected: wake due to an ULP wake after 5 seconds.
Actual: wakes due to (a fallback) timer wake after 20 seconds.

If using this code with ESP-IDF directly then it works as expected.
If using this code in a version before 2.0.14, then it works as expected.
If disabling the ADC read operation in the ULP code, then it works as expected.

More details at https://github.com/ayavilevich/ulp_adc_issue_ard_min/blob/main/README.md

Sketch

https://github.com/ayavilevich/ulp_adc_issue_ard_min/blob/main/src/main.cpp

Above can can be used with Arduino IDE, PIO or ESP-IDF.

Debug Message

Output, Arduino ESP32 3.2.0


ets Jul 29 2019 12:21:46

rst:0x1 (POWERON_RESET),boot:0x13 (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:0x3fff0030,len:4888
load:0x40078000,len:16516
load:0x40080400,len:4
load:0x40080404,len:3476
entry 0x400805b4
ESP-IDF: 5.4.1, ESP Arduino: 3.2.0
Start
Chip revision: 301
Not ULP/timer wakeup
TEST: sleeping for 20 sec
Entering deep sleep
ets Jul 29 2019 12:21:46

rst:0x5 (DEEPSLEEP_RESET),boot:0x13 (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:0x3fff0030,len:4888
load:0x40078000,len:16516
load:0x40080400,len:4
load:0x40080404,len:3476
entry 0x400805b4
ESP-IDF: 5.4.1, ESP Arduino: 3.2.0
Start
Chip revision: 301
Timer wakeup
Deep sleep wakeup
ULP do adc 1
ULP start counter: 2
ULP wake counter: 2
TEST: sleeping for 20 sec
Entering deep sleep


Output, Arduino ESP32 3.2.0 with ADC read disabled


ets Jul 29 2019 12:21:46

rst:0x1 (POWERON_RESET),boot:0x13 (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:0x3fff0030,len:4888
load:0x40078000,len:16516
load:0x40080400,len:4
load:0x40080404,len:3476
entry 0x400805b4
ESP-IDF: 5.4.1, ESP Arduino: 3.2.0
Start
Chip revision: 301
Not ULP/timer wakeup
TEST: sleeping for 20 sec
Entering deep sleep
ets Jul 29 2019 12:21:46

rst:0x5 (DEEPSLEEP_RESET),boot:0x13 (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:0x3fff0030,len:4888
load:0x40078000,len:16516
load:0x40080400,len:4
load:0x40080404,len:3476
entry 0x400805b4
ESP-IDF: 5.4.1, ESP Arduino: 3.2.0
Start
Chip revision: 301
ULP wakeup
Deep sleep wakeup
ULP do adc 0
ULP start counter: 51
ULP wake counter: 50
TEST: sleeping for 20 sec
Entering deep sleep


Output, ESP-IDF 4.4.6


ets Jul 29 2019 12:21:46

rst:0x1 (POWERON_RESET),boot:0x13 (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:2
load:0x3fff0030,len:5484
ho 0 tail 12 room 4
load:0x40078000,len:14824
ho 0 tail 12 room 4
load:0x40080400,len:3460
0x40080400: _init at ??:?

entry 0x40080638
ESP-IDF: 4.4.6
Start
Chip revision: 3, full: 301
Not ULP/timer wakeup
TEST: sleeping for 20 sec
Entering deep sleep
ets Jul 29 2019 12:21:46

rst:0x5 (DEEPSLEEP_RESET),boot:0x13 (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:2
load:0x3fff0030,len:5484
ho 0 tail 12 room 4
load:0x40078000,len:14824
ho 0 tail 12 room 4
load:0x40080400,len:3460
0x40080400: _init at ??:?

entry 0x40080638
ESP-IDF: 4.4.6
Start
Chip revision: 3, full: 301
ULP wakeup
Deep sleep wakeup
ULP do adc 1
ULP start counter: 51
ULP wake counter: 50
TEST: sleeping for 20 sec
Entering deep sleep

Other Steps to Reproduce

also tried on another ESP32 board. it made no difference.

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

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

[ayavilevich]

To clarify, the indication of the ULP getting "stuck" is that the "start" and "wake" counters are not increasing as expected. See them getting the value of 2 at the point the device woke due to a timer. So just 2 invocations of the ULP program in 20 seconds.

[Jason2866]

I don't see the settings ulp_low_thr = 1500; ulp_high_thr = 2000 in your code.

[ayavilevich]

I don't see the settings ulp_low_thr = 1500; ulp_high_thr = 2000 in your code.

There are no such settings in this project. You are probably confusing this with the "ulp_adc" example in ESP-IDF SDK.
examples/system/ulp/ulp_fsm/ulp_adc/main/ulp_adc_example_main.c

This POC is somewhat based on that code but the ULP program is different. It is ULP MACROs instead of ULP assembly, so there are no "c variables". You have 4 settings in RTC_SLOW_MEM. See:

#define U_MEM_START_COUNTER 0 // use as index to RTC_SLOW_MEM
#define U_MEM_WAKEUP_COUNTER 1
#define U_MEM_WAKEUP_COUNTER_GOAL 2
#define U_MEM_DO_ADC 3

I couldn't find a way to run the ESP-IDF ulp_adc example as-is on Arduino.

[Jason2866]

I do understand this but the values 1500 and 2000 are nowhere applied in your code. I think the are needed, because the are there in IDF example.

[ayavilevich]

Those thresholds are used in another project where the ULP code compares the ADC reading with the thresholds. In the POC of this issue the value of the ADC is not used nor compared with anything.

This reproduce code is a different ulp program than the one in ulp_adc.

[SuGlider]

@ayavilevich - This is not an Arduino issue. It is about ULP ASM and how to implement a specific project. I'll move it to discussion.

I think that the ULP has never completed running the ASM code.
It seems to miss esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON); in order to define how the power domain for the ULP will behave when the ESP32 goes into deep sleep. By default, when the ESP32 deep sleeps, the ULP is not powered.

But I didn't try out the project, just took a quick look.
ULP will run at about 8MHz. It is slow. The ULP is started and right after that the ESP32 goes into deep sleep, which may stop the ULP automatically.

You can check this example from Arduino to see how the ESP32 ULP is used (maybe already done it?)
https://github.com/espressif/arduino-esp32/blob/master/libraries/ESP32/examples/DeepSleep/SmoothBlink_ULP_Code/SmoothBlink_ULP_Code.ino

[ayavilevich]

This is not an Arduino issue. It is about ULP ASM and how to implement a specific project. I'll move it to discussion.

@SuGlider This might not be an Arduino issue but this is an Arduino-esp32 issue. This code works in esp-idf but not in recent Arduino-esp32. Also, this code works fine with Arduino-ESP32 version before 2.0.14 .

This is not about ULP ASM. To be precise, ULP macros are used instead of ULP ASM directly.

I think that the ULP has never completed running the ASM code.

It completes fine if not using ADC or if using esp-idf or if using an older Arduino-ESP32 version.

It seems to miss esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON); in order to define how the power domain for the ULP will behave when the ESP32 goes into deep sleep. By default, when the ESP32 deep sleeps, the ULP is not powered.

The default for this setting is AUTO. Forcing this to ON doesn't make a difference. Please check to confirm this is not only on my end.

But I didn't try out the project, just took a quick look.

Please try the project to confirm the findings.

ULP will run at about 8MHz. It is slow. The ULP is started and right after that the ESP32 goes into deep sleep, which may stop the ULP automatically.

If we don't perform an ADC operation in the ULP code then all works. For me it means that generic ULP works fine with the provided setup. If it stops, then it only does that when using ADC and the specific Arduino-ESP32 SDK version.

You can check this example from Arduino to see how the ESP32 ULP is used (maybe already done it?)
https://github.com/espressif/arduino-esp32/blob/master/libraries/ESP32/examples/DeepSleep/SmoothBlink_ULP_Code/SmoothBlink_ULP_Code.ino

This is a great example, and the code is similar to the one I prepared except the example doesn't use ADC. It uses digital pins which doesn't create the issue described.

[SuGlider]

@ayavilevich - After testing it I have concluded, as you say, that I_ADC() macro gets stuck with Arduino Core 3.2.1, which doesn't happen with Arduino Core 2.0.x.
I have tested it with Arduino Core 3.0.0 with IDF 5.1. It also stops with I_ADC().

This seems to be due to an IDF 5 internal change. Its ADC Driver has change a lot.
The legacy IDF 4 ADC Driver seems to not work with ULP in deep sleep mode anymore.
Nothing that Arduino Core Implementation could solve.

[SuGlider]

You may try building it using Arduino as IDF Component with IDF 5.4.2 and Arduino Core 3.2.1.
Not sure if this would solve anything.

[SuGlider]

You may try building it using Arduino as IDF Component with IDF 5.4.2 and Arduino Core 3.2.1. Not sure if this would solve anything.

I have ust tested it using Arduino as IDF component with the minimum sdkconfig settings possible to verify that no current extra settings would cause the issue. But it also doesn't work.

Therefore, I'd say that IDF has changed somthing that make it fail. Most probably related to ADC driver changes which are incompatible with legacy and ULP.

The best way to move forward would be trying to go with the IDF 5.4.2 examples and move all to IDF with ULP ASM.

[ayavilevich]

@ayavilevich - After testing it I have concluded, as you say, that I_ADC() macro gets stuck with Arduino Core 3.2.1, which doesn't happen with Arduino Core 2.0.x. I have tested it with Arduino Core 3.0.0 with IDF 5.1. It also stops with I_ADC().

This seems to be due to an IDF 5 internal change. Its ADC Driver has change a lot. The legacy IDF 4 ADC Driver seems to not work with ULP in deep sleep mode anymore. Nothing that Arduino Core Implementation could solve.

@SuGlider thanks for spending time to reproduce this.
I have nailed it down to transition between Arduino-esp32 2.0.13 and 2.0.14 . Both IDF 4 (4.4.5 and 4.4.6 respectfully). So I don't think IDF 5 plays a role and it does happen (for me) with Arduino Code 2.0.x just 2.0.14 and newer. Do you think there could be another explanation?
I would go and open an issue with the esp-idf repo but this whole code works in just esp-idf... Please advise.