Peripherals

The peripherals library provides a light hardware abstraction layer to manage the GPIO, UART, SPI and I²C peripherals. It also provides miscellaneous functions for time and numbers.

The provided version targets the Arduino and compatible SDKs, with a C-like syntax for all the functions. The technical note Migrate to another SDK describes how to adapt the library to other SDKs.

On the Commercial edition, the strings could be either the String object provided by the Arduino SDK, or the C-standard char array supported by the cstring library. The option is set on the configuration header file. On the Basic edition, only the Arduino SDK option is provided.

Legacy version 6

Deprecated functions and synonyms have been removed from the peripherals library.

For more information, please refer to Migrate from release 6 to release 7.

On the Evaluation, Commercial and Viewer editions, the architecture of the peripherals library consists of two layers:

• The top layer with the library hV_HAL_Peripherals exposes all the functions, with hV_HAL as prefix, to the other libraries and application code;

• The underlying layer with SDK- or API-specific library hV_SDK_Peripherals includes the limited set of functions specific to the SDK or API, with hV_SDK as prefix, to be ported when using another SDK or API.

On the Basic edition, the architecture of the peripherals library consists of one single layer:

• The library hV_HAL_Peripherals exposes all the functions, with hV_HAL as prefix, to the other libraries and application code. Using another SDK or API requires porting those functions.

Warning

All the other libraries and the application code shall call the functions from hV_HAL_Peripherals, with hV_HAL as prefix.

Configure

#include "hV_HAL_Peripherals.h"

The pre-processor statement includes the peripherals library.

hV_HAL_begin();

hV_HAL_begin() proceeds with the general initialisation. It configures and starts the peripherals GPIO, UART, SPI, and I²C if needed.

Use

For each peripheral, the library exposes a limited set of functions with a C-like syntax.

The names of the functions start with hV_HAL, then the peripherals like _GPIO, and finally the command like _begin(), to form hV_HAL_GPIO_begin().

GPIO

hV_HAL_GPIO_begin();

hV_HAL_GPIO_define(PIN1, OUTPUT);
hV_HAL_GPIO_set(PIN1);
hV_HAL_GPIO_clear(PIN1);
// hV_HAL_GPIO_write(PIN1, HIGH);

hV_HAL_GPIO_define(PIN2, INPUT_PULLUP);
uint8_t result = hV_HAL_GPIO_get(PIN2);
// uint8_t result = hV_HAL_GPIO_read(PIN2);

hV_HAL_GPIO_begin() initialises the GPIO peripherals.

hV_HAL_GPIO_define() defines the pin as output or input, with pull-up or pull-down options.

hV_HAL_GPIO_set() and hV_HAL_GPIO_clear() turns the pin as output high and low, with hV_HAL_GPIO_write() as synonym

hV_HAL_GPIO_get() reads the value from the pins as input, with hV_HAL_GPIO_read() as synonym.

Serial

hV_HAL_Serial_begin(115200);

hV_HAL_Serial_begin() initialises the UART interface.

hV_HAL_Serial_printf("Value= %i", 0);
hV_HAL_Serial_crlf();

The resulting line sent to the console is

Value= 0

hV_HAL_Serial_printf() sends a format and the values. It corresponds to the standard function printf().

hV_HAL_Serial_crlf() performs a carriage return and line feed.

SPI

hV_HAL_SPI_begin();

uint8_t answer = hV_HAL_SPI_transfer(data);

hV_HAL_SPI_begin() configures the SPI bus at 8 MHz, MSB first, and launches it.

hV_HAL_SPI_transfer() sends data and receives an answer.

Optionally,

hV_HAL_SPI_end();
//
hV_HAL_SPI_begin();

hV_HAL_SPI_end() deactivates the SPI bus, to be reactivated with hV_HAL_SPI_begin().

3-wire SPI

The 3-wire SPI bus is a variant of the SPI bus with a unique bi-directional data line.

hV_HAL_SPI3_define(pinSCK, pinSDIO);

hV_HAL_SPI3_begin();

hV_HAL_SPI3_define() defines the GPIOs for the clock and data in-out signals.

hV_HAL_SPI3_begin() configures and launches the 3-wire SPI bus.

hV_HAL_GPIO_clear(b_pin.panelDC); // Command
hV_HAL_GPIO_clear(b_pin.panelCS); // Select
hV_HAL_SPI3_write(0xb9);
hV_HAL_delayMilliseconds(5);

hV_HAL_GPIO_set(b_pin.panelDC); // Data
ui8 = hV_HAL_SPI3_read(); // Read
hV_HAL_GPIO_set(b_pin.panelCS); // Unselect

hV_HAL_SPI3_write and hV_HAL_SPI3_read() writes and reads data to and from the 3-wire SPI bus.

I²C

I²C is also called Wire.

hV_HAL_Wire_begin();

hV_HAL_Wire_transfer(address, data, sizeData, answer, sizeAnswer);

hV_HAL_Wire_begin() configures the I²C bus in fast mode at 400 kHz and launches it.

hV_HAL_Wire_transfer() connects to the I²C device at the specified address, sends the data and optionnally retrieves the answer.

Optionally,

hV_HAL_Wire_end();
// ...
hV_HAL_Wire_begin();

hV_HAL_Wire_end() deactivates the I²C bus, to be reactivated with hV_HAL_Wire_begin().

Time

hV_HAL_delayMicroseconds(100);
hV_HAL_delayMilliseconds(100);
uint32_t chrono32 = hV_HAL_getMilliseconds();

hV_HAL_delayMicroseconds() performs a blocking delay of the specified duration in microseconds. hV_HAL_delayMilliseconds() performs a non-blocking delay of the specified duration in milliseconds.

hV_HAL_getMilliseconds() returns the number of milliseconds since the start of the system. As a 32-bit integer, it is limited to ~50 days.

Log system

The log system displays messages with a level to the UART interface.

The UART interface is initialised by hV_HAL_begin().

hV_HAL_log(LEVEL_INFO, "Value= %i", 1);

hV_HAL_log() sends a log message with a level, a format and the values.

The resulting line sent to the console is

hV . Value= 1

Level	Symbol	Details
LEVEL_CRITICAL	*	Non-handled error
LEVEL_ERROR	+	Handled error
LEVEL_WARNING	!	Warning
LEVEL_INFO	.	Information
LEVEL_DEBUG	-	Debug
LEVEL_SYSTEM	=	System
LEVEL_USER	>	User

Option	Details
WITH_COMMENT	Line starting with //
WITH_NO_CRLF	No carriage return-line feed
WITH_NO_LEVEL	Level not printed
WITH_CHRONO	Chronometer in s.ms

hV_HAL_log(LEVEL_INFO | WITH_COMMENT, "Value= %i", 2);
hV_HAL_log(LEVEL_INFO | WITH_NO_CRLF, "Value= %i and ", 3);
hV_HAL_log(LEVEL_INFO | WITH_NO_LEVEL, "Value= %i", 4);

The resulting lines sent to the console are

// hV . Value= 2
hV . Value= 3 and Value= 4

hV_HAL_setFilter(LEVEL_CRITICAL | LEVEL_ERROR);

hV_HAL_setFilter() sets a filter to the messages and prints those with the mentioned levels.

The example above will only print the messages with a critical or an error level.

hV_HAL_setOption(WITH_COMMENT);
hV_HAL_log(LEVEL_INFO, "Value= %i", 5);
hV_HAL_setOption(WITH_COMMENT | WITH_CHRONO);
hV_HAL_log(LEVEL_INFO, "Value= %i", 6);

hV_HAL_setOption() defines a default option for all the messages sent.

The resulting line sent to the console is

// hV . Value= 5
// hV .        1.551 Value= 6

Note

hV_HAL_setFilter() and hV_HAL_setOption() can be set before calling hV_HAL_begin().

Miscellaneous

uint32_t random hV_HAL_random(maxNumber);

hV_HAL_random() generates a pseudo-random number between 0 and maxNumber - 1, both included.

int32_t outputValue = hV_HAL_map(inputValue, inputMin, inputMax, outputMin, outputMax)

hV_HAL_map() scales a value.

Formula is

Terminate

hV_HAL_end();

hV_HAL_end() enters an endless loop for micro-controllers or exits with a 0 value for Linux. It corresponds to hV_HAL_exit(0).

hV_HAL_exit(code);

hV_HAL_exit(code) displays the code value, and enters an endless loop for micro-controllers or exits with the code value for Linux.

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See also

• Migrate to another SDK