Diff: targets/TARGET_NORDIC/TARGET_MCU_NRF51822/i2c_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NORDIC/TARGET_MCU_NRF51822/i2c_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,309 @@
+/* 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 "twi_master.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 = NULL;
+  
+    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");
+    }
+
+	twi_master_init_and_clear(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);
+}