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/* mbed Microcontroller Library
* Copyright (c) 2013 Nordic Semiconductor
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mbed_assert.h"
#include "i2c_api.h"
#include "cmsis.h"
#include "pinmap.h"
#include "mbed_error.h"
// nRF51822's I2C_0 and SPI_0 (I2C_1, SPI_1 and SPIS1) share the same address.
// They can't be used at the same time. So we use two global variable to track the usage.
// See nRF51822 address information at nRF51822_PS v2.0.pdf - Table 15 Peripheral instance reference
volatile i2c_spi_peripheral_t i2c0_spi0_peripheral = {0, 0, 0, 0};
volatile i2c_spi_peripheral_t i2c1_spi1_peripheral = {0, 0, 0, 0};
void i2c_interface_enable(i2c_t *obj)
{
obj->i2c->ENABLE = (TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos);
}
void twi_master_init(i2c_t *obj, PinName sda, PinName scl, int frequency)
{
NRF_GPIO->PIN_CNF[scl] = ((GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos) |
(GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos) |
(GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos) |
(GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) |
(GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos));
NRF_GPIO->PIN_CNF[sda] = ((GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos) |
(GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos) |
(GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos) |
(GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) |
(GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos));
obj->i2c->PSELSCL = scl;
obj->i2c->PSELSDA = sda;
// set default frequency at 100k
i2c_frequency(obj, frequency);
i2c_interface_enable(obj);
}
void i2c_init(i2c_t *obj, PinName sda, PinName scl)
{
NRF_TWI_Type *i2c;
if (i2c0_spi0_peripheral.usage == I2C_SPI_PERIPHERAL_FOR_I2C &&
i2c0_spi0_peripheral.sda_mosi == (uint8_t)sda &&
i2c0_spi0_peripheral.scl_miso == (uint8_t)scl) {
// The I2C with the same pins is already initialized
i2c = (NRF_TWI_Type *)I2C_0;
obj->peripheral = 0x1;
} else if (i2c1_spi1_peripheral.usage == I2C_SPI_PERIPHERAL_FOR_I2C &&
i2c1_spi1_peripheral.sda_mosi == (uint8_t)sda &&
i2c1_spi1_peripheral.scl_miso == (uint8_t)scl) {
// The I2C with the same pins is already initialized
i2c = (NRF_TWI_Type *)I2C_1;
obj->peripheral = 0x2;
} else if (i2c0_spi0_peripheral.usage == 0) {
i2c0_spi0_peripheral.usage = I2C_SPI_PERIPHERAL_FOR_I2C;
i2c0_spi0_peripheral.sda_mosi = (uint8_t)sda;
i2c0_spi0_peripheral.scl_miso = (uint8_t)scl;
i2c = (NRF_TWI_Type *)I2C_0;
obj->peripheral = 0x1;
} else if (i2c1_spi1_peripheral.usage == 0) {
i2c1_spi1_peripheral.usage = I2C_SPI_PERIPHERAL_FOR_I2C;
i2c1_spi1_peripheral.sda_mosi = (uint8_t)sda;
i2c1_spi1_peripheral.scl_miso = (uint8_t)scl;
i2c = (NRF_TWI_Type *)I2C_1;
obj->peripheral = 0x2;
} else {
// No available peripheral
error("No available I2C");
}
obj->i2c = i2c;
obj->scl = scl;
obj->sda = sda;
obj->i2c->EVENTS_ERROR = 0;
obj->i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
obj->i2c->POWER = 0;
for (int i = 0; i<100; i++) {
}
obj->i2c->POWER = 1;
twi_master_init(obj, sda, scl, 100000);
}
void i2c_reset(i2c_t *obj)
{
obj->i2c->EVENTS_ERROR = 0;
obj->i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
obj->i2c->POWER = 0;
for (int i = 0; i<100; i++) {
}
obj->i2c->POWER = 1;
twi_master_init(obj, obj->sda, obj->scl, obj->freq);
}
int i2c_start(i2c_t *obj)
{
int status = 0;
i2c_reset(obj);
obj->address_set = 0;
return status;
}
int i2c_stop(i2c_t *obj)
{
int timeOut = 100000;
obj->i2c->EVENTS_STOPPED = 0;
// write the stop bit
obj->i2c->TASKS_STOP = 1;
while (!obj->i2c->EVENTS_STOPPED) {
timeOut--;
if (timeOut<0) {
return 1;
}
}
obj->address_set = 0;
i2c_reset(obj);
return 0;
}
int i2c_do_write(i2c_t *obj, int value)
{
int timeOut = 100000;
obj->i2c->TXD = value;
while (!obj->i2c->EVENTS_TXDSENT) {
timeOut--;
if (timeOut<0) {
return 1;
}
}
obj->i2c->EVENTS_TXDSENT = 0;
return 0;
}
int i2c_do_read(i2c_t *obj, char *data, int last)
{
int timeOut = 100000;
if (last) {
// To trigger stop task when a byte is received,
// must be set before resume task.
obj->i2c->SHORTS = 2;
}
obj->i2c->TASKS_RESUME = 1;
while (!obj->i2c->EVENTS_RXDREADY) {
timeOut--;
if (timeOut<0) {
return 1;
}
}
obj->i2c->EVENTS_RXDREADY = 0;
*data = obj->i2c->RXD;
return 0;
}
void i2c_frequency(i2c_t *obj, int hz)
{
if (hz<250000) {
obj->freq = 100000;
obj->i2c->FREQUENCY = (TWI_FREQUENCY_FREQUENCY_K100 << TWI_FREQUENCY_FREQUENCY_Pos);
} else if (hz<400000) {
obj->freq = 250000;
obj->i2c->FREQUENCY = (TWI_FREQUENCY_FREQUENCY_K250 << TWI_FREQUENCY_FREQUENCY_Pos);
} else {
obj->freq = 400000;
obj->i2c->FREQUENCY = (TWI_FREQUENCY_FREQUENCY_K400 << TWI_FREQUENCY_FREQUENCY_Pos);
}
}
int checkError(i2c_t *obj)
{
if (obj->i2c->EVENTS_ERROR == 1) {
if (obj->i2c->ERRORSRC & TWI_ERRORSRC_ANACK_Msk) {
obj->i2c->EVENTS_ERROR = 0;
obj->i2c->TASKS_STOP = 1;
return I2C_ERROR_BUS_BUSY;
}
obj->i2c->EVENTS_ERROR = 0;
obj->i2c->TASKS_STOP = 1;
return I2C_ERROR_NO_SLAVE;
}
return 0;
}
int i2c_read(i2c_t *obj, int address, char *data, int length, int stop)
{
int status, count, errorResult;
obj->i2c->ADDRESS = (address >> 1);
obj->i2c->SHORTS = 1; // to trigger suspend task when a byte is received
obj->i2c->EVENTS_RXDREADY = 0;
obj->i2c->TASKS_STARTRX = 1;
// Read in all except last byte
for (count = 0; count < (length - 1); count++) {
status = i2c_do_read(obj, &data[count], 0);
if (status) {
errorResult = checkError(obj);
i2c_reset(obj);
if (errorResult<0) {
return errorResult;
}
return count;
}
}
// read in last byte
status = i2c_do_read(obj, &data[length - 1], 1);
if (status) {
i2c_reset(obj);
return length - 1;
}
// If not repeated start, send stop.
if (stop) {
while (!obj->i2c->EVENTS_STOPPED) {
}
obj->i2c->EVENTS_STOPPED = 0;
}
return length;
}
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop)
{
int status, errorResult;
obj->i2c->ADDRESS = (address >> 1);
obj->i2c->SHORTS = 0;
obj->i2c->TASKS_STARTTX = 1;
for (int i = 0; i<length; i++) {
status = i2c_do_write(obj, data[i]);
if (status) {
i2c_reset(obj);
errorResult = checkError(obj);
if (errorResult<0) {
return errorResult;
}
return i;
}
}
// If not repeated start, send stop.
if (stop) {
if (i2c_stop(obj)) {
return I2C_ERROR_NO_SLAVE;
}
}
return length;
}
int i2c_byte_read(i2c_t *obj, int last)
{
char data;
int status;
status = i2c_do_read(obj, &data, last);
if (status) {
i2c_reset(obj);
}
return data;
}
int i2c_byte_write(i2c_t *obj, int data)
{
int status = 0;
if (!obj->address_set) {
obj->address_set = 1;
obj->i2c->ADDRESS = (data >> 1);
if (data & 1) {
obj->i2c->EVENTS_RXDREADY = 0;
obj->i2c->SHORTS = 1;
obj->i2c->TASKS_STARTRX = 1;
} else {
obj->i2c->SHORTS = 0;
obj->i2c->TASKS_STARTTX = 1;
}
} else {
status = i2c_do_write(obj, data);
if (status) {
i2c_reset(obj);
}
}
return (1 - status);
}
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