Lee Kai Xuan
mbed-os
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Diff: targets/TARGET_NXP/TARGET_LPC176X/i2c_api.c
- Revision:
- 0:f269e3021894
diff -r 000000000000 -r f269e3021894 targets/TARGET_NXP/TARGET_LPC176X/i2c_api.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC176X/i2c_api.c Sun Oct 23 15:10:02 2016 +0000
@@ -0,0 +1,407 @@
+/* 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 "mbed_assert.h"
+#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},
+ {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},
+ {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 << 7; break;
+ case I2C_1: LPC_SC->PCONP |= 1 << 19; break;
+ case I2C_2: LPC_SC->PCONP |= 1 << 26; 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));
+
+ // Clear old status and wait for Serial Interrupt.
+ i2c_clear_SI(obj);
+ i2c_wait_SI(obj);
+
+ // Obtain new status.
+ status = i2c_status(obj);
+
+ 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;
+ addr = ((uint32_t)obj->i2c) + I2C_addr_offset[1][idx];
+ *((uint32_t *) addr) = mask & 0xFE;
+ }
+}