HULP

HULP is a helper library for the ESP32's Ultra Low Power Co-Processor (ULP).

Features

Memory Access

Easily access variables to store and retrieve data, or share between the ULP and SoC

RTC_SLOW_ATTR ulp_var_t my_ulp_variable;

// ULP:
I_MOVI(R2, 0),
I_GET(R1, R2, my_ulp_variable), // Load my_ulp_variable into R1
I_PUT(R3, R2, my_ulp_variable), // Store R3 into my_ulp_variable

// SoC:
uint16_t temp = my_ulp_variable.val;
my_ulp_variable.val = 123;

GPIO

Functions to configure GPIOs in preparation for the ULP

hulp_configure_pin(GPIO_NUM_25, RTC_GPIO_MODE_INPUT_ONLY, GPIO_PULLUP_ONLY, 0);
hulp_configure_pin(GPIO_NUM_26, RTC_GPIO_MODE_OUTPUT_ONLY, GPIO_FLOATING, 1);
hulp_configure_analog_pin(GPIO_NUM_33, ADC_ATTEN_DB_11, ADC_WIDTH_BIT_12);

Countless macros to simplify ULP GPIO operations

I_GPIO_READ(GPIO_NUM_27),       // Digital read
I_GPIO_SET(GPIO_NUM_25, 1),     // Set digital output level high
I_ANALOG_READ(R0, GPIO_NUM_33), // Analog read
I_GPIO_PULLUP(GPIO_NUM_26, 1),  // Enable internal pullup

As well as advanced functionality, including interrupts

// Configure edge interrupt:
hulp_configure_pin_int(GPIO_NUM_32, GPIO_INTR_ANYEDGE);
// ULP:
I_GPIO_INT_RD(GPIO_NUM_32),   // Check if interrupt has triggered
I_GPIO_INT_CLR(GPIO_NUM_32),  // Clear interrupt

Timing

Macros for basic delays

M_DELAY_US_10_100(72),    // Delay 72uS
M_DELAY_MS_20_1000(500),  // Delay 500mS

HULP also introduces a concept that makes use of the RTC slow clock for complex, asynchronous timing operations, useful for very power efficient operation and multitasking without the need for blocking delays. See Timing example.

Peripherals

Helpers and drivers for internal peripherals as well as communication protocols, including:

• Capacitive Touch

• Hall Effect

• Temperature

• Hardware I2C

• Software (bitbanged) I2C

• APA RGB LED

• UART

• HX711

Debugging

• Insert breakpoints, track and manipulate ULP program flow, inspect or alter register contents via the SoC

• Combine the UART driver with included ULP PRINTF subroutines to communicate debugging information independent of the SoC (even in deep sleep!)

And much more...

Check out the examples for some programs demonstrating the possibilities of the ULP with HULP.

There's a lot more to HULP than what is mentioned above - in lieu of better documentation, please see relevant header files for more features and information.

Compatibility

HULP uses the C macro (legacy) programming method (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/ulp_macros.html), however you are free to copy and convert any parts for use with the ULP binary toolchain.

ESP-IDF >=4.2.0 is required, and there is partial support for Arduino-ESP32 >=2.0.0.

Only ESP32 is currently supported.