radio.c

/*
 * Library to control Silicon Laboratories SI6342 radio
 * Author: Adrian Studer
 * License: CC BY-SA Creative Commons Attribution-ShareAlike
 *          https://creativecommons.org/licenses/by-sa/4.0/
 *          Please contact the author if you want to use this work in a closed-source project
 */

#include <msp430.h>
#include <inttypes.h>

#include "radio.h"
#include "radio_config.h"
#include "spi.h"

#define	SPI_NSEL	BIT4						// chip select on pin 1.4
#define SPI_ON		P1OUT &= ~SPI_NSEL;			// turn SPI on (NSEL=0)
#define SPI_OFF		P1OUT |= SPI_NSEL;			// turn SPI off (NSEL=1)

#define CMD_NOP						0x00
#define CMD_PART_INFO				0x01
#define CMD_POWER_UP				0x02
#define CMD_FUNC_INFO				0x10
#define CMD_SET_PROPERTY			0x11
#define CMD_GET_PROPERTY			0x12
#define CMD_GPIO_PIN_CONFIG			0x13
#define CMD_GET_ADC_READING			0x14
#define CMD_FIFO_INFO				0x15
#define CMD_PACKET_INFO				0x16
#define CMD_IRCAL					0x17
#define CMD_PROTOCOL_CFG			0x18
#define CMD_GET_INT_STATUS			0x20
#define CMD_GET_PH_STATUS			0x21
#define CMD_GET_MODEM_STATUS		0x22
#define CMD_GET_CHIP_STATUS			0x23
#define CMD_START_RX				0x32
#define CMD_REQUEST_DEVICE_STATE	0x33
#define CMD_CHANGE_STATE			0x34
#define CMD_RX_HOP					0x36
#define CMD_READ_CMD_BUFF			0x44
#define CMD_FRR_A_READ				0x50
#define CMD_READ_RX_FIFO			0x77

// radio configuration as generated by WDS and stored in radio_config.h
const uint8_t radio_configuration[] = RADIO_CONFIGURATION_DATA_ARRAY;

// radio image rejection calibration sequence (as per datasheet)
const uint8_t radio_ircal_sequence_coarse[] = { 0x56, 0x10, 0xCA, 0xF0 };
const uint8_t radio_ircal_sequence_fine[] = { 0x13, 0x10, 0xCA, 0xF0 };

union radio_buffer_u radio_buffer;

static void send_command(uint8_t cmd, const uint8_t *send_buffer, uint8_t send_length, uint8_t response_length);
static int receive_result(uint8_t length);

// configure I/O pins used for radio
void radio_setup(void)
{
	// initialize SPI pins
	P1SEL &= ~SPI_NSEL;								// NSEL pin as I/O
	P1DIR |= SPI_NSEL;								// set NSEL pin to output
	SPI_OFF;										// turn off chip select

	spi_init();

	// initialize CTS pin as input
	RADIO_PSEL &= ~(RADIO_CTS);						// CTS pin is I/O
	RADIO_PDIR &= ~(RADIO_CTS);						// CTS pin is input

	// initialize shutdown pin as output
	RADIO_PSEL &= ~RADIO_SDN;						// shutdown pin is I/O
	RADIO_PDIR |= RADIO_SDN;						// shutdown pin is output

	return;
}

// shut down radio, call radio_configure to restart
void radio_shutdown(void)
{
	// initialize shutdown pin
	RADIO_PSEL &= ~RADIO_SDN;							// shutdown pin is I/O
	RADIO_PDIR |= RADIO_SDN;								// shutdown pin is output

	// SDN high = turn off radio
	RADIO_POUT |= RADIO_SDN;
}

// reset radio and load configuration data
void radio_configure(void)
{
	// reset radio: SDN=1, wait >1us, SDN=0
	RADIO_POUT |= RADIO_SDN;
	_delay_cycles(1000);
	RADIO_POUT &= ~RADIO_SDN;

	while (!RADIO_READY);						// wait for chip to wake up

	// transfer radio configuration
	const uint8_t *cfg = radio_configuration;
	while (*cfg)	{							// configuration array stops with 0
		char count = (*cfg++) - 1;				// 1st byte: number of bytes, incl. command
		char cmd = *cfg++;						// 2nd byte: command
		send_command(cmd, cfg, count, 0);		// send bytes to chip
		cfg += count;							// point at next line
		while (!RADIO_READY);					// wait for chip to complete operation
	}

	return;
}

// directly set individual radio property
void radio_set_property(uint8_t prop_group,	uint8_t prop_num, uint8_t value)
{
	radio_buffer.data[0] = prop_group;
	radio_buffer.data[1] = 1;
	radio_buffer.data[2] = prop_num;
	radio_buffer.data[3] = value;
	send_command(CMD_SET_PROPERTY, radio_buffer.data, 4, 0);
	return;
}

// invoke radio image rejection self-calibration
void radio_calibrate_ir(void)
{
	// send calibration sequence as per datasheet - doing it wrong, read AN790
	// note: looking at si446x_ircal.c in provided examples, CMD_IRCAL has 3 undocumented return values CAL_STATE, RSSI, DIR_CH
	// note2: don't use this method, rely on WDS to generate proper calibration sequence
	radio_start_rx(0,0,0,0,0,0);
	send_command(CMD_IRCAL, radio_ircal_sequence_coarse, sizeof(radio_ircal_sequence_coarse), 0);
	send_command(CMD_IRCAL, radio_ircal_sequence_fine, sizeof(radio_ircal_sequence_fine), 0);
	while (!RADIO_READY);						// wait for calibration to complete
}

// retrieve radio device information (e.g. chip model)
void radio_part_info(void)
{
	send_command(CMD_PART_INFO, 0, 0, sizeof(radio_buffer.part_info));
}

// retrieve radio function revision information
void radio_func_info(void)
{
	send_command(CMD_FUNC_INFO, 0, 0, sizeof(radio_buffer.func_info));
}

// retrieve radio FIFO information
void radio_fifo_info(uint8_t reset_fifo)
{
	radio_buffer.data[0] = reset_fifo;
	send_command(CMD_FIFO_INFO, radio_buffer.data, 1, sizeof(radio_buffer.fifo_info));
}

// retrieve radio interrupt status information
void radio_get_int_status(uint8_t ph_clr_pending, uint8_t modem_clr_pending, uint8_t chip_clr_pending)
{
	radio_buffer.data[0] = ph_clr_pending;
	radio_buffer.data[1] = modem_clr_pending;
	radio_buffer.data[2] = chip_clr_pending;
	send_command(CMD_GET_INT_STATUS, radio_buffer.data, 3, sizeof(radio_buffer.int_status));
}

// retrieve radio packet handler status information
void radio_get_ph_status(uint8_t clr_pending)
{
	radio_buffer.data[0] = clr_pending;
	send_command(CMD_GET_PH_STATUS, radio_buffer.data, 1, sizeof(radio_buffer.ph_status));
}

// retrieve radio chip status information
void radio_get_chip_status(uint8_t clr_pending)
{
	radio_buffer.data[0] = clr_pending;
	send_command(CMD_GET_CHIP_STATUS, radio_buffer.data, 1, sizeof(radio_buffer.chip_status));
}

// retrieve radio modem status information
void radio_get_modem_status(uint8_t clr_pending)
{
	radio_buffer.data[0] = clr_pending;
	send_command(CMD_GET_MODEM_STATUS, radio_buffer.data, 1, sizeof(radio_buffer.modem_status));
}

// read fast read registers, results in radio_buffer.data[0..3], frr = start register 'A'..'D', count = # of values
void radio_frr_read(uint8_t frr, uint8_t count)
{
	while (!RADIO_READY);					// always wait for radio to be ready (CTS) before sending next command

	// implemented directly as FRR access has no CTS handshake
	SPI_ON;

	spi_transfer(CMD_FRR_A_READ + ((frr-1) & 0x03));	// transmit command, start register

	uint8_t i = 0;
	while (i < count) {
		radio_buffer.data[i] = spi_transfer(0);		// receive bytes
		i++;
	}

	SPI_OFF;
}

// put radio in receive state
void radio_start_rx(uint8_t channel, uint8_t start_condition, uint16_t rx_length, uint8_t rx_timeout_state,	uint8_t rx_valid_state,	uint8_t rx_invalid_state)
{
	radio_buffer.data[0] = channel;
	radio_buffer.data[1] = start_condition;
	radio_buffer.data[2] = rx_length >> 8;
	radio_buffer.data[3] = rx_length & 0xff;
	radio_buffer.data[4] = rx_timeout_state;
	radio_buffer.data[5] = rx_valid_state;
	radio_buffer.data[6] = rx_invalid_state;
	send_command(CMD_START_RX, radio_buffer.data, 7, 0);
}

// wait for radio to complete previous command
void radio_wait_for_CTS(void)
{
	while (!RADIO_READY);				// wait for radio to be ready before returning
}

// read radio state
void radio_request_device_state(void)
{
	send_command(CMD_REQUEST_DEVICE_STATE, 0, 0, sizeof(radio_buffer.device_state));
}

// change radio state, e.g. from receive to ready
void radio_change_state(uint8_t next_state)
{
	radio_buffer.data[0] = next_state;
	send_command(CMD_CHANGE_STATE, radio_buffer.data, 1, 0);
}

// read various radio status and information registers
void radio_debug(void)
{
	radio_get_int_status(0, 0, 0);
	radio_get_chip_status(0);
	radio_get_modem_status(0);
	radio_part_info();
	radio_func_info();
	radio_request_device_state();
}

// send command, including optional parameters if sendBuffer != 0
void send_command(uint8_t cmd, const uint8_t *send_buffer, uint8_t send_length, uint8_t response_length)
{
	while (!RADIO_READY);					// always wait for radio to be ready (CTS) before sending next command

	SPI_ON;

	spi_transfer(cmd);						// transmit command

	if (send_length && send_buffer) {		// if there are parameters to send, do so
		uint8_t c = 0;
		while (c != send_length) {
			spi_transfer(send_buffer[c]);	// transmit byte
			c++;
		}
	}

	SPI_OFF;

	if (response_length) {
		while (!RADIO_READY);				// wait for radio to be ready before retrieving response
		while (receive_result(response_length) == 0);	// wait for valid response
	}
	return;
}

// read result: write 44h, read CTS byte, if 0xff read result bytes, else loop (cycle NSEL)
int receive_result(uint8_t length)
{
	SPI_ON;

	spi_transfer(CMD_READ_CMD_BUFF);		// send 0x44 to receive data/CTS
	if(spi_transfer(0) != 0xff)	{			// if CTS is not 0xff
		SPI_OFF;
		return 0;							// data not ready yet
	}

	uint8_t i = 0;							// data ready, read result into buffer
	while (i < length) {
		radio_buffer.data[i] = spi_transfer(0);		// receive byte
		i++;
	}

	SPI_OFF;

	return 1;						// data received
}