ESP32-ULP-Temp-Sensor/main.S at master · rickyringler/ESP32-ULP-Temp-Sensor · GitHub

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; https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/system/ulp_instruction_set.html
; Registers:
; General Purpose, 16-bit: R0, R1, R2, R3
; Stage Count, 8-bit
; Instruction Counter

#include "soc/soc_ulp.h"
#include "soc/sens_reg.h"
#include "soc/rtc_cntl_reg.h"
#include "sdkconfig.h"

    .data

    .global entry
    .global temp_array
    .global min_temp_thresh
    .global max_temp_thresh
    buffer: .short 3
    min_temp_thresh: .short -135
    max_temp_thresh: .short 450
    .set measure_cycles, 1000
    .set sleep_cycles, 5000

    .bss
    .align 4
    temp_array:
       .short  0
       .short  0
       .short  0

    sum: .short

    .text
    .align 4

    entry:
        jump cpu_ready ;don't move a fucking muscle unless the CPU wants to be our friend
    init_buffer:
        move r0, buffer ;init array of 3 bytes (3 elements)
        move r1, 0 ;we'll use this shit later
    get_temperature:
        tsens r2, measure_cycles
        st r2, temp_array[r1]
    check_buffer:
        add r1, r1, 1
        sub r0, r0, 1
        wait sleep_cycles
        jumpr get_temperature, r0, ne ;bool. keep getting temp data
    add_elements:
        move r3, 0
        ld r2, temp_array[0]
        add r3, r3, r2
        ld r2, temp_array[1]
        add r3, r3, r2
        ld r2, temp_array[2]
        add r3, r3, r2
        move r0, r3
        ld r1, min_temp_thresh
        sub r2, r0, r1
        jumpr temperature_failure, min_temp_thresh, le
        ld r1, max_temp_thresh
        sub r2, r0, r1
        jumpr temperature_failure, max_temp_thresh, ge
        jump entry
    temperature_failure:
        halt
    cpu_ready:
      READ_RTC_REG(RTC_CNTL_LOW_POWER_ST_REG, 27, 1)
      move r1, r0
      move r0, 0
      READ_RTC_FIELD(RTC_CNTL_LOW_POWER_ST_REG, RTC_CNTL_RDY_FOR_WAKEUP)
      and r0, r0, r1 ;bool. we only want to use this if the CPU is awake and can receive a tx from ULP
      wait sleep_cycles
      jumpr init_buffer, r0, eq ;bool. r0=r0 (0)
      jump cpu_ready ;loop