ESP32-S3 ULP-FSM SENS_ register r/w problem

[rhgoll]

Board

Heltec ESP32 Lora (V3)

Device Description

ESP32-S3 with SX1262 Lora module

Hardware Configuration

nothing

Version

other

IDE Name

PlatformIO

Operating System

Windows 11 22H2

Flash frequency

40Mhz

PSRAM enabled

no

Upload speed

460800

Description

If I read or set the SENS_SAR_PERI_CLK_GATE_CONF_REG from ULP code, it seems not working (but I get no error message).
If I read or set it from the main CPU, it works.

I am using ULP FSM C macro in PlatformIO Arduino framework.
The framework is a custom built from esp-idf 4.4.4, with added support of ULP:

CONFIG_ESP32S3_ULP_COPROC_ENABLED=y
CONFIG_ESP32S3_ULP_COPROC_RESERVE_MEM=512

This code snippet in the sketch is only a small part of an older big project running on ESP32.
The remaining ULP-FSM code (not showed here) ported from the ESP32 is working without problem, only this new register manipulation don't work.

Sketch

#include "Arduino.h"
#include "soc/rtc_cntl_reg.h"
#include "soc/rtc_io_reg.h"
#include "soc/sens_reg.h"
#include "driver/rtc_io.h"
#include "esp32s3/ulp.h"

#define _v(val) ((uint32_t)(&val-RTC_SLOW_MEM))

RTC_NOINIT_ATTR uint32_t rtc_slow_debug_sens1;
RTC_NOINIT_ATTR uint32_t rtc_slow_debug_sens2;
RTC_NOINIT_ATTR uint32_t rtc_slow_debug_sens_cpu;
RTC_NOINIT_ATTR uint32_t rtc_slow_ulp_finished;

const ulp_insn_t program[] =
{
  I_MOVI(R3,_v(rtc_slow_debug_sens1)),
  I_RD_REG(SENS_SAR_PERI_CLK_GATE_CONF_REG,0,15),
  I_STL(R0,R3,0),
  I_RD_REG(SENS_SAR_PERI_CLK_GATE_CONF_REG,16,31),
  I_STH(R0,R3,0),
  I_WR_REG_BIT(SENS_SAR_PERI_CLK_GATE_CONF_REG,SENS_IOMUX_CLK_EN_S,1),
  I_MOVI(R3,_v(rtc_slow_debug_sens2)),
  I_RD_REG(SENS_SAR_PERI_CLK_GATE_CONF_REG,0,15),
  I_STL(R0,R3,0),
  I_RD_REG(SENS_SAR_PERI_CLK_GATE_CONF_REG,16,31),
  I_STH(R0,R3,0),
  I_MOVI(R3,_v(rtc_slow_ulp_finished)),
  I_MOVI(R0,1),
  I_STL(R0,R3,0),
  I_END(),
  I_HALT()
};

size_t load_addr = 0;
size_t size = sizeof(program)/sizeof(ulp_insn_t);

String toBinary(uint32_t num);

void setup()
{
  Serial.begin(115200);
  rtc_slow_ulp_finished=0;
  Serial.println("Starting ULP...");
  ulp_process_macros_and_load(load_addr, program, &size);
  ulp_run(load_addr);   
  delay(100); //wait for ulp to finish
  Serial.printf("ULP finished: %d\n",rtc_slow_ulp_finished);
  Serial.println("PERI_REG before ULP setting: "+toBinary(rtc_slow_debug_sens1));
  Serial.println("PERI_REG after ULP setting: "+toBinary(rtc_slow_debug_sens2));
  
  rtc_slow_debug_sens_cpu=READ_PERI_REG(SENS_SAR_PERI_CLK_GATE_CONF_REG);
  Serial.println("PERI_REG before CPU setting: "+toBinary(rtc_slow_debug_sens_cpu));
  rtc_gpio_init(GPIO_NUM_4);
  rtc_slow_debug_sens_cpu=READ_PERI_REG(SENS_SAR_PERI_CLK_GATE_CONF_REG);
  Serial.println("PERI_REG after CPU setting: "+toBinary(rtc_slow_debug_sens_cpu)); 
}

void loop()
{
}

String toBinary(uint32_t num)
{
    String binary;
    for (uint8_t i=31;i>0;i--)
    {
      binary+=bitRead(num,i);
    }
    return binary;
}

Debug Message

Starting ULP...
ULP finished: 1
PERI_REG before ULP setting: 0010000000000000000000000000000
PERI_REG after ULP setting: 0010000000000000000000000000000
PERI_REG before CPU setting: 0000000000000000000000000000000
PERI_REG after CPU setting: 1000000000000000000000000000000

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.

[wnienhaus]

I can confirm this unexpected behaviour also on an ESP32-S2. Writing to SENS_SAR_PERI_CLK_GATE_CONF_REG from the ULP-FSM has no effect.

I wonder if this is expected behaviour on the S2/S3, but so far I cannot find anything in the Technical Reference Manual that would explain this behaviour as expected.

[wnienhaus]

Actually correction: On the ESP32S2, the register is called SENS_SAR_IO_MUX_CONF_REG - and that's the one I cannot write to from the ULP. But looking at this example in the ESP-IDF it should work (I would assume they that code wouldn't be there, if it's not meant to work).

[Llgok]

Yes, I encountered the same issue with ULP counting on ESP32S3 using Arduino. It was unable to count properly. However, when using examples on ESP-IDF, the ULP functionality worked correctly.

[wnienhaus]

Actually... what I encountered was a bug in an earlier ESP-IDF. It was fixed in June 2023 by this PR: espressif/esp-idf#11652.

So, for anyone still running into this, make sure your Arduino toolchain uses an ESP-IDF later than June 2023 and it should work.

(For anyone using the micropython-esp32-ulp assembler, the same bug was fixed here: micropython/micropython-esp32-ulp@ed28d27).

[Parsaabasi]

Hello,

Due to the overwhelming volume of issues currently being addressed, we have decided to close the previously received tickets. If you still require assistance or if the issue persists, please don't hesitate to reopen the ticket.

Thanks.