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 elopes
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/*
* Copyright (C) 2016 Freie Universitรคt Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @ingroup cpu_nrf51
* @ingroup drivers_periph_i2c
* @{
*
* @file
* @brief Low-level I2C driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
/**
* @ingroup cpu_nrf51
* @ingroup drivers_periph_i2c
* @{
*
* @file
* @brief Low-level I2V driver implementation
*
* @}
*/
#include "cpu.h"
#include "mutex.h"
#include "assert.h"
#include "periph/i2c.h"
#include "periph_conf.h"
#define ENABLE_DEBUG (0)
#include "debug.h"
#ifdef I2C_NUMOF
/**
* @brief If any of the 4 lower bits are set, the speed value is invalid
*/
#define INVALID_SPEED_MASK (0x0f)
/**
* @brief Initialized bus locks (we have a maximum of two devices...)
*/
static mutex_t locks[] = {
MUTEX_INIT,
MUTEX_INIT
};
static inline NRF_TWI_Type *dev(i2c_t bus)
{
return i2c_config[bus].dev;
}
static int error(i2c_t bus)
{
DEBUG("[i2c] error 0x%02x\n", (int)dev(bus)->ERRORSRC);
dev(bus)->ERRORSRC = (TWI_ERRORSRC_DNACK_Clear |
TWI_ERRORSRC_ANACK_Clear |
TWI_ERRORSRC_OVERRUN_Clear);
dev(bus)->EVENTS_ERROR = 0;
return -1;
}
static int write(i2c_t bus, uint8_t addr, const void *data, int len, int stop)
{
uint8_t *buf = (uint8_t *)data;
assert((bus <= I2C_NUMOF) && (len > 0));
DEBUG("i2c: writing %i byte to the bus\n", len);
dev(bus)->ADDRESS = (addr & 0x7f);
for (int i = 0; i < len; i++) {
dev(bus)->TXD = *buf++;
dev(bus)->EVENTS_TXDSENT = 0;
dev(bus)->TASKS_STARTTX = 1;
while (!(dev(bus)->EVENTS_TXDSENT) && !(dev(bus)->EVENTS_ERROR)) {}
if (dev(bus)->EVENTS_ERROR) {
return error(bus);
}
}
if (stop) {
dev(bus)->EVENTS_STOPPED = 0;
dev(bus)->TASKS_STOP = 1;
while (!(dev(bus)->EVENTS_STOPPED) && !(dev(bus)->EVENTS_ERROR)) {}
if (dev(bus)->EVENTS_ERROR) {
return error(bus);
}
}
return len;
}
int i2c_init_master(i2c_t bus, i2c_speed_t speed)
{
if (bus >= I2C_NUMOF) {
return -1;
}
if (speed & INVALID_SPEED_MASK) {
return -2;
}
/* power on the bus */
dev(bus)->POWER = TWI_POWER_POWER_Enabled;
/* pin configuration */
NRF_GPIO->PIN_CNF[i2c_config[bus].pin_scl] = (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos);
NRF_GPIO->PIN_CNF[i2c_config[bus].pin_scl] = (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos);
dev(bus)->PSELSCL = i2c_config[bus].pin_scl;
dev(bus)->PSELSDA = i2c_config[bus].pin_sda;
NRF_PPI->CHENCLR = (1 << i2c_config[bus].ppi);
NRF_PPI->CH[i2c_config[bus].ppi].EEP = (uint32_t)&dev(bus)->EVENTS_BB;
/* bus clock speed configuration */
dev(bus)->FREQUENCY = speed;
/* enable the device */
dev(bus)->ENABLE = TWI_ENABLE_ENABLE_Enabled;
return 0;
}
int i2c_acquire(i2c_t bus)
{
assert(bus <= I2C_NUMOF);
mutex_lock(&locks[bus]);
return 0;
}
int i2c_release(i2c_t bus)
{
assert(bus <= I2C_NUMOF);
mutex_unlock(&locks[bus]);
return 0;
}
int i2c_read_byte(i2c_t bus, uint8_t address, void *data)
{
return i2c_read_bytes(bus, address, data, 1);
}
int i2c_read_bytes(i2c_t bus, uint8_t address, void *data, int length)
{
uint8_t *in_buf = (uint8_t *)data;
assert((bus <= I2C_NUMOF) && (length > 0));
DEBUG("[i2c] reading %i byte from the bus\n", length);
/* set the client address */
dev(bus)->ADDRESS = (address & 0x7f);
/* setup PPI channel as alternative to the broken SHORTS
* -> see PAN notice #36: "Shortcuts described in nRF51 Reference Manual are
* not functional." */
if (length == 1) {
NRF_PPI->CH[i2c_config[bus].ppi].TEP = (uint32_t)&dev(bus)->TASKS_STOP;
}
else {
NRF_PPI->CH[i2c_config[bus].ppi].TEP = (uint32_t)&dev(bus)->TASKS_SUSPEND;
}
NRF_PPI->CHENSET = (1 << i2c_config[bus].ppi);
dev(bus)->EVENTS_RXDREADY = 0;
dev(bus)->EVENTS_STOPPED = 0;
dev(bus)->TASKS_STARTRX = 1;
for (int i = (length - 1); i >= 0; i--) {
while (!(dev(bus)->EVENTS_RXDREADY) && !(dev(bus)->EVENTS_ERROR)) {}
if (dev(bus)->EVENTS_ERROR) {
return error(bus);
}
*in_buf++ = (uint8_t)dev(bus)->RXD;
if (i == 1) {
NRF_PPI->CH[i2c_config[bus].ppi].TEP = (uint32_t)&dev(bus)->TASKS_STOP;
}
dev(bus)->EVENTS_RXDREADY = 0;
dev(bus)->TASKS_RESUME = 1;
}
/* wait for the device to finish up */
while (dev(bus)->EVENTS_STOPPED == 0) {}
NRF_PPI->CHENCLR = (1 << i2c_config[bus].ppi);
return length;
}
int i2c_read_reg(i2c_t bus, uint8_t address, uint8_t reg, void *data)
{
write(bus, address, ®, 1, 0);
return i2c_read_bytes(bus, address, data, 1);
}
int i2c_read_regs(i2c_t bus, uint8_t address, uint8_t reg,
void *data, int length)
{
write(bus, address, ®, 1, 0);
return i2c_read_bytes(bus, address, data, length);
}
int i2c_write_byte(i2c_t bus, uint8_t address, uint8_t data)
{
return write(bus, address, &data, 1, 1);
}
int i2c_write_bytes(i2c_t bus, uint8_t address, const void *data, int length)
{
return write(bus, address, data, length, 1);
}
int i2c_write_reg(i2c_t bus, uint8_t address, uint8_t reg, uint8_t data)
{
write(bus, address, ®, 1, 0);
return write(bus, address, &data, 1, 1);
}
int i2c_write_regs(i2c_t bus, uint8_t address, uint8_t reg,
const void *data, int length)
{
write(bus, address, ®, 1, 0);
return write(bus, address, data, length, 1);
}
#endif /* I2C_NUMOF */
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