Diff: targets/hal/TARGET_NXP/TARGET_LPC81X/TARGET_LPC81X_COMMON/i2c_api.c

Revision:

20:4263a77256ae

Parent:

13:0645d8841f51

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_NXP/TARGET_LPC81X/TARGET_LPC81X_COMMON/i2c_api.c	Tue Sep 10 15:14:19 2013 +0300
@@ -0,0 +1,242 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * 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 "i2c_api.h"
+#include "cmsis.h"
+#include "pinmap.h"
+#include "error.h"
+
+static const SWM_Map SWM_I2C_SDA[] = {
+    {7, 24},
+};
+
+static const SWM_Map SWM_I2C_SCL[] = {
+    {8, 0},
+};
+
+static uint8_t repeated_start = 0;
+
+#define I2C_DAT(x)          (x->i2c->MSTDAT)
+#define I2C_STAT(x)         ((x->i2c->STAT >> 1) & (0x07))
+
+static inline int i2c_status(i2c_t *obj) {
+    return I2C_STAT(obj);
+}
+
+// Wait until the Serial Interrupt (SI) is set
+static int i2c_wait_SI(i2c_t *obj) {
+    int timeout = 0;
+    while (!(obj->i2c->STAT & (1 << 0))) {
+        timeout++;
+        if (timeout > 100000) return -1;
+    }
+    return 0;
+}
+
+static inline void i2c_interface_enable(i2c_t *obj) {
+    obj->i2c->CFG |= (1 << 0);
+}
+
+static inline void i2c_power_enable(i2c_t *obj) {
+    LPC_SYSCON->SYSAHBCLKCTRL |= (1<<5);	
+    LPC_SYSCON->PRESETCTRL &= ~(0x1<<6);
+    LPC_SYSCON->PRESETCTRL |= (0x1<<6);
+}
+
+void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
+    obj->i2c = (LPC_I2C_TypeDef *)LPC_I2C;
+    
+    const SWM_Map *swm;
+    uint32_t regVal;
+    
+    swm = &SWM_I2C_SDA[0];
+    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
+    LPC_SWM->PINASSIGN[swm->n] = regVal |  (sda   << swm->offset);
+    
+    swm = &SWM_I2C_SCL[0];
+    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
+    LPC_SWM->PINASSIGN[swm->n] = regVal |  (scl   << swm->offset);
+    
+    // enable power
+    i2c_power_enable(obj);
+    // set default frequency at 100k
+    i2c_frequency(obj, 100000);
+    i2c_interface_enable(obj);
+}
+
+inline int i2c_start(i2c_t *obj) {
+    int status = 0;
+    if (repeated_start) {
+        obj->i2c->MSTCTL = (1 << 1) | (1 << 0);
+        repeated_start = 0;
+    } else {
+        obj->i2c->MSTCTL = (1 << 1);
+    }
+    return status;
+}
+
+inline int i2c_stop(i2c_t *obj) {
+    int timeout = 0;
+
+    obj->i2c->MSTCTL = (1 << 2) | (1 << 0);
+    while ((obj->i2c->STAT & ((1 << 0) | (7 << 1))) != ((1 << 0) | (0 << 1))) {
+        timeout ++;
+        if (timeout > 100000) return 1;
+    }
+
+    return 0;
+}
+
+
+static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
+    // write the data
+    I2C_DAT(obj) = value;
+    
+    if (!addr)
+        obj->i2c->MSTCTL = (1 << 0);
+    
+    // wait and return status
+    i2c_wait_SI(obj);
+    return i2c_status(obj);
+}
+
+static inline int i2c_do_read(i2c_t *obj, int last) {
+    // wait for it to arrive
+    i2c_wait_SI(obj);
+    if (!last)
+        obj->i2c->MSTCTL = (1 << 0);
+    
+    // return the data
+    return (I2C_DAT(obj) & 0xFF);
+}
+
+void i2c_frequency(i2c_t *obj, int hz) {
+    // No peripheral clock divider on the M0
+    uint32_t PCLK = SystemCoreClock;
+    
+    uint32_t clkdiv = PCLK / (hz * 4) - 1;
+    
+    obj->i2c->DIV = clkdiv;
+    obj->i2c->MSTTIME = 0;
+}
+
+// The I2C does a read or a write as a whole operation
+// There are two types of error conditions it can encounter
+//  1) it can not obtain the bus
+//  2) it gets error responses at part of the transmission
+//
+// We tackle them as follows:
+//  1) we retry until we get the bus. we could have a "timeout" if we can not get it
+//      which basically turns it in to a 2)
+//  2) on error, we use the standard error mechanisms to report/debug
+//
+// Therefore an I2C transaction should always complete. If it doesn't it is usually
+// because something is setup wrong (e.g. wiring), and we don't need to programatically
+// check for that
+
+int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
+    int count, status;
+    
+    i2c_start(obj);
+    
+    status = i2c_do_write(obj, (address | 0x01), 1);
+    if (status != 0x01) {
+        i2c_stop(obj);
+        return I2C_ERROR_NO_SLAVE;
+    }
+    
+    // Read in all except last byte
+    for (count = 0; count < (length - 1); count++) {
+        int value = i2c_do_read(obj, 0);
+        status = i2c_status(obj);
+        if (status != 0x00) {
+            i2c_stop(obj);
+            return count;
+        }
+        data[count] = (char) value;
+    }
+    
+    // read in last byte
+    int value = i2c_do_read(obj, 1);
+    status = i2c_status(obj);
+    if (status != 0x01) {
+        i2c_stop(obj);
+        return length - 1;
+    }
+    
+    data[count] = (char) value;
+    
+    // If not repeated start, send stop.
+    if (stop) {
+        i2c_stop(obj);
+    } else {
+        repeated_start = 1;
+    }
+    
+    return length;
+}
+
+int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
+    int i, status;
+    
+    i2c_start(obj);
+    
+    status = i2c_do_write(obj, (address & 0xFE), 1);
+    if (status != 0x02) {
+        i2c_stop(obj);
+        return I2C_ERROR_NO_SLAVE;
+    }
+    
+    for (i=0; i<length; i++) {
+        status = i2c_do_write(obj, data[i], 0);
+        if (status != 0x02) {
+            i2c_stop(obj);
+            return i;
+        }
+    }
+    
+    // If not repeated start, send stop.
+    if (stop) {
+        i2c_stop(obj);
+    } else {
+        repeated_start = 1;
+    }
+    
+    return length;
+}
+
+void i2c_reset(i2c_t *obj) {
+    i2c_stop(obj);
+}
+
+int i2c_byte_read(i2c_t *obj, int last) {
+    return (i2c_do_read(obj, last) & 0xFF);
+}
+
+int i2c_byte_write(i2c_t *obj, int data) {
+    int ack;
+    int status = i2c_do_write(obj, (data & 0xFF), 0);
+    
+    switch(status) {
+        case 2:
+            ack = 1;
+            break;
+        default:
+            ack = 0;
+            break;
+    }
+
+    return ack;
+}