Diff: targets/TARGET_NXP/TARGET_LPC2460/i2c_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC2460/i2c_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,405 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2015 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"
+
+static const PinMap PinMap_I2C_SDA[] = {
+    {P0_0 , I2C_1, 3},
+    {P0_10, I2C_2, 2},
+    {P0_19, I2C_1, 3},
+    {P0_27, I2C_0, 1},
+    {P2_14, I2C_1, 3},
+    {P2_30, I2C_2, 3},
+    {P4_20, I2C_2, 2},
+    {NC   , NC   , 0}
+};
+
+static const PinMap PinMap_I2C_SCL[] = {
+    {P0_1 , I2C_1, 3},
+    {P0_11, I2C_2, 2},
+    {P0_20, I2C_1, 3},
+    {P0_28, I2C_0, 1},
+    {P2_15, I2C_1, 3},
+    {P2_31, I2C_2, 3},
+    {P4_21, I2C_2, 2},
+    {NC   , NC,    0}
+};
+
+#define I2C_CONSET(x)       (x->i2c->I2CONSET)
+#define I2C_CONCLR(x)       (x->i2c->I2CONCLR)
+#define I2C_STAT(x)         (x->i2c->I2STAT)
+#define I2C_DAT(x)          (x->i2c->I2DAT)
+#define I2C_SCLL(x, val)    (x->i2c->I2SCLL = val)
+#define I2C_SCLH(x, val)    (x->i2c->I2SCLH = val)
+
+static const uint32_t I2C_addr_offset[2][4] = {
+    {0x0C, 0x20, 0x24, 0x28},
+    {0x30, 0x34, 0x38, 0x3C}
+};
+
+static inline void i2c_conclr(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
+    I2C_CONCLR(obj) = (start << 5)
+                    | (stop << 4)
+                    | (interrupt << 3)
+                    | (acknowledge << 2);
+}
+
+static inline void i2c_conset(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
+    I2C_CONSET(obj) = (start << 5)
+                    | (stop << 4)
+                    | (interrupt << 3)
+                    | (acknowledge << 2);
+}
+
+// Clear the Serial Interrupt (SI)
+static inline void i2c_clear_SI(i2c_t *obj) {
+    i2c_conclr(obj, 0, 0, 1, 0);
+}
+
+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 (!(I2C_CONSET(obj) & (1 << 3))) {
+        timeout++;
+        if (timeout > 100000) return -1;
+    }
+    return 0;
+}
+
+static inline void i2c_interface_enable(i2c_t *obj) {
+    I2C_CONSET(obj) = 0x40;
+}
+
+static inline void i2c_power_enable(i2c_t *obj) {
+    switch ((int)obj->i2c) {
+        case I2C_0: LPC_SC->PCONP |= 1 << PCI2C0; break;
+        case I2C_1: LPC_SC->PCONP |= 1 << PCI2C1; break;
+        case I2C_2: LPC_SC->PCONP |= 1 << PCI2C2; break;
+    }
+}
+
+void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
+    // determine the SPI to use
+    I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
+    I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);
+    obj->i2c = (LPC_I2C_TypeDef *)pinmap_merge(i2c_sda, i2c_scl);
+    MBED_ASSERT((int)obj->i2c != NC);
+    
+    // enable power
+    i2c_power_enable(obj);
+    
+    // set default frequency at 100k
+    i2c_frequency(obj, 100000);
+    i2c_conclr(obj, 1, 1, 1, 1);
+    i2c_interface_enable(obj);
+    
+    pinmap_pinout(sda, PinMap_I2C_SDA);
+    pinmap_pinout(scl, PinMap_I2C_SCL);
+}
+
+inline int i2c_start(i2c_t *obj) {
+    int status = 0;
+    int isInterrupted = I2C_CONSET(obj) & (1 << 3);
+
+    // 8.1 Before master mode can be entered, I2CON must be initialised to:
+    //  - I2EN STA STO SI AA - -
+    //  -  1    0   0   x  x - -
+    // if AA = 0, it can't enter slave mode
+    i2c_conclr(obj, 1, 1, 0, 1);
+
+    // The master mode may now be entered by setting the STA bit
+    // this will generate a start condition when the bus becomes free
+    i2c_conset(obj, 1, 0, 0, 1);
+    // Clearing SI bit when it wasn't set on entry can jump past state
+    // 0x10 or 0x08 and erroneously send uninitialized slave address.
+    if (isInterrupted)
+        i2c_clear_SI(obj);
+
+    i2c_wait_SI(obj);
+    status = i2c_status(obj);
+
+    // Clear start bit now that it's transmitted
+    i2c_conclr(obj, 1, 0, 0, 0);
+    return status;
+}
+
+inline int i2c_stop(i2c_t *obj) {
+    int timeout = 0;
+
+    // write the stop bit
+    i2c_conset(obj, 0, 1, 0, 0);
+    i2c_clear_SI(obj);
+    
+    // wait for STO bit to reset
+    while (I2C_CONSET(obj) & (1 << 4)) {
+        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;
+    
+    // clear SI to init a send
+    i2c_clear_SI(obj);
+    
+    // wait and return status
+    i2c_wait_SI(obj);
+    return i2c_status(obj);
+}
+
+static inline int i2c_do_read(i2c_t *obj, int last) {
+    // we are in state 0x40 (SLA+R tx'd) or 0x50 (data rx'd and ack)
+    if (last) {
+        i2c_conclr(obj, 0, 0, 0, 1); // send a NOT ACK
+    } else {
+        i2c_conset(obj, 0, 0, 0, 1); // send a ACK
+    }
+    
+    // accept byte
+    i2c_clear_SI(obj);
+    
+    // wait for it to arrive
+    i2c_wait_SI(obj);
+    
+    // return the data
+    return (I2C_DAT(obj) & 0xFF);
+}
+
+void i2c_frequency(i2c_t *obj, int hz) {
+    // [TODO] set pclk to /4
+    uint32_t PCLK = SystemCoreClock / 4;
+    
+    uint32_t pulse = PCLK / (hz * 2);
+    
+    // I2C Rate
+    I2C_SCLL(obj, pulse);
+    I2C_SCLH(obj, pulse);
+}
+
+// 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;
+    
+    status = i2c_start(obj);
+    
+    if ((status != 0x10) && (status != 0x08)) {
+        i2c_stop(obj);
+        return I2C_ERROR_BUS_BUSY;
+    }
+    
+    status = i2c_do_write(obj, (address | 0x01), 1);
+    if (status != 0x40) {
+        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 != 0x50) {
+            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 != 0x58) {
+        i2c_stop(obj);
+        return length - 1;
+    }
+    
+    data[count] = (char) value;
+    
+    // If not repeated start, send stop.
+    if (stop) {
+        i2c_stop(obj);
+    }
+    
+    return length;
+}
+
+int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
+    int i, status;
+    
+    status = i2c_start(obj);
+    
+    if ((status != 0x10) && (status != 0x08)) {
+        i2c_stop(obj);
+        return I2C_ERROR_BUS_BUSY;
+    }
+    
+    status = i2c_do_write(obj, (address & 0xFE), 1);
+    if (status != 0x18) {
+        i2c_stop(obj);
+        return I2C_ERROR_NO_SLAVE;
+    }
+    
+    for (i=0; i<length; i++) {
+        status = i2c_do_write(obj, data[i], 0);
+        if (status != 0x28) {
+            i2c_stop(obj);
+            return i;
+        }
+    }
+    
+    // clearing the serial interrupt here might cause an unintended rewrite of the last byte
+    // see also issue report https://mbed.org/users/mbed_official/code/mbed/issues/1
+    // i2c_clear_SI(obj);
+    
+    // If not repeated start, send stop.
+    if (stop) {
+        i2c_stop(obj);
+    }
+    
+    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 0x18: case 0x28:       // Master transmit ACKs
+            ack = 1;
+            break;
+        
+        case 0x40:                  // Master receive address transmitted ACK
+            ack = 1;
+            break;
+        
+        case 0xB8:                  // Slave transmit ACK
+            ack = 1;
+            break;
+        
+        default:
+            ack = 0;
+            break;
+    }
+    
+    return ack;
+}
+
+void i2c_slave_mode(i2c_t *obj, int enable_slave) {
+    if (enable_slave != 0) {
+        i2c_conclr(obj, 1, 1, 1, 0);
+        i2c_conset(obj, 0, 0, 0, 1);
+    } else {
+        i2c_conclr(obj, 1, 1, 1, 1);
+    }
+}
+
+int i2c_slave_receive(i2c_t *obj) {
+    int status;
+    int retval;
+    
+    status = i2c_status(obj);
+    switch(status) {
+        case 0x60: retval = 3; break;
+        case 0x70: retval = 2; break;
+        case 0xA8: retval = 1; break;
+        default  : retval = 0; break;
+    }
+    
+    return(retval);
+}
+
+int i2c_slave_read(i2c_t *obj, char *data, int length) {
+    int count = 0;
+    int status;
+    
+    do {
+        i2c_clear_SI(obj);
+        i2c_wait_SI(obj);
+        status = i2c_status(obj);
+        if((status == 0x80) || (status == 0x90)) {
+            data[count] = I2C_DAT(obj) & 0xFF;
+        }
+        count++;
+    } while (((status == 0x80) || (status == 0x90) ||
+            (status == 0x060) || (status == 0x70)) && (count < length));
+    
+    if(status != 0xA0) {
+        i2c_stop(obj);
+    }
+    
+    i2c_clear_SI(obj);
+    
+    return count;
+}
+
+int i2c_slave_write(i2c_t *obj, const char *data, int length) {
+    int count = 0;
+    int status;
+    
+    if(length <= 0) {
+        return(0);
+    }
+    
+    do {
+        status = i2c_do_write(obj, data[count], 0);
+        count++;
+    } while ((count < length) && (status == 0xB8));
+    
+    if((status != 0xC0) && (status != 0xC8)) {
+        i2c_stop(obj);
+    }
+    
+    i2c_clear_SI(obj);
+    
+    return(count);
+}
+
+void i2c_slave_address(i2c_t *obj, int idx, uint32_t address, uint32_t mask) {
+    uint32_t addr;
+    
+    if ((idx >= 0) && (idx <= 3)) {
+        addr = ((uint32_t)obj->i2c) + I2C_addr_offset[0][idx];
+        *((uint32_t *) addr) = address & 0xFF;
+    }
+}