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mbed-os/targets/TARGET_NXP/TARGET_LPC23XX/can_api.c

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/* 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 "can_api.h"
#include "cmsis.h"
#include "pinmap.h"
#include <math.h>
#include <string.h>
/* Acceptance filter mode in AFMR register */
#define ACCF_OFF 0x01
#define ACCF_BYPASS 0x02
#define ACCF_ON 0x00
#define ACCF_FULLCAN 0x04
/* There are several bit timing calculators on the internet.
http://www.port.de/engl/canprod/sv_req_form.html
http://www.kvaser.com/can/index.htm
*/
static const PinMap PinMap_CAN_RD[] = {
{P0_0 , CAN_1, 1},
{P0_4 , CAN_2, 2},
{P0_21, CAN_1, 3},
{P2_7 , CAN_2, 1},
{NC , NC , 0}
};
static const PinMap PinMap_CAN_TD[] = {
{P0_1 , CAN_1, 1},
{P0_5 , CAN_2, 2},
{P0_22, CAN_1, 3},
{P2_8 , CAN_2, 1},
{NC , NC , 0}
};
// Type definition to hold a CAN message
struct CANMsg {
unsigned int reserved1 : 16;
unsigned int dlc : 4; // Bits 16..19: DLC - Data Length Counter
unsigned int reserved0 : 10;
unsigned int rtr : 1; // Bit 30: Set if this is a RTR message
unsigned int type : 1; // Bit 31: Set if this is a 29-bit ID message
unsigned int id; // CAN Message ID (11-bit or 29-bit)
unsigned char data[8]; // CAN Message Data Bytes 0-7
};
typedef struct CANMsg CANMsg;
static uint32_t can_disable(can_t *obj) {
uint32_t sm = obj->dev->MOD;
obj->dev->MOD |= 1;
return sm;
}
static inline void can_enable(can_t *obj) {
if (obj->dev->MOD & 1) {
obj->dev->MOD &= ~(1);
}
}
int can_mode(can_t *obj, CanMode mode) {
return 0; // not implemented
}
int can_filter(can_t *obj, uint32_t id, uint32_t mask, CANFormat format, int32_t handle) {
return 0; // not implemented
}
static int can_pclk(can_t *obj) {
int value = 0;
switch ((int)obj->dev) {
case CAN_1: value = (LPC_SC->PCLKSEL0 & (0x3 << 26)) >> 26; break;
case CAN_2: value = (LPC_SC->PCLKSEL0 & (0x3 << 28)) >> 28; break;
}
switch (value) {
case 1: return 1;
case 2: return 2;
case 3: return 6;
default: return 4;
}
}
// This table has the sampling points as close to 75% as possible. The first
// value is TSEG1, the second TSEG2.
static const int timing_pts[23][2] = {
{0x0, 0x0}, // 2, 50%
{0x1, 0x0}, // 3, 67%
{0x2, 0x0}, // 4, 75%
{0x3, 0x0}, // 5, 80%
{0x3, 0x1}, // 6, 67%
{0x4, 0x1}, // 7, 71%
{0x5, 0x1}, // 8, 75%
{0x6, 0x1}, // 9, 78%
{0x6, 0x2}, // 10, 70%
{0x7, 0x2}, // 11, 73%
{0x8, 0x2}, // 12, 75%
{0x9, 0x2}, // 13, 77%
{0x9, 0x3}, // 14, 71%
{0xA, 0x3}, // 15, 73%
{0xB, 0x3}, // 16, 75%
{0xC, 0x3}, // 17, 76%
{0xD, 0x3}, // 18, 78%
{0xD, 0x4}, // 19, 74%
{0xE, 0x4}, // 20, 75%
{0xF, 0x4}, // 21, 76%
{0xF, 0x5}, // 22, 73%
{0xF, 0x6}, // 23, 70%
{0xF, 0x7}, // 24, 67%
};
static unsigned int can_speed(unsigned int sclk, unsigned int pclk, unsigned int cclk, unsigned char psjw) {
uint32_t btr;
uint16_t brp = 0;
uint32_t calcbit;
uint32_t bitwidth;
int hit = 0;
int bits;
bitwidth = sclk / (pclk * cclk);
brp = bitwidth / 0x18;
while ((!hit) && (brp < bitwidth / 4)) {
brp++;
for (bits = 22; bits > 0; bits--) {
calcbit = (bits + 3) * (brp + 1);
if (calcbit == bitwidth) {
hit = 1;
break;
}
}
}
if (hit) {
btr = ((timing_pts[bits][1] << 20) & 0x00700000)
| ((timing_pts[bits][0] << 16) & 0x000F0000)
| ((psjw << 14) & 0x0000C000)
| ((brp << 0) & 0x000003FF);
} else {
btr = 0xFFFFFFFF;
}
return btr;
}
void can_init(can_t *obj, PinName rd, PinName td) {
CANName can_rd = (CANName)pinmap_peripheral(rd, PinMap_CAN_RD);
CANName can_td = (CANName)pinmap_peripheral(td, PinMap_CAN_TD);
obj->dev = (LPC_CAN_TypeDef *)pinmap_merge(can_rd, can_td);
MBED_ASSERT((int)obj->dev != NC);
switch ((int)obj->dev) {
case CAN_1: LPC_SC->PCONP |= 1 << 13; break;
case CAN_2: LPC_SC->PCONP |= 1 << 14; break;
}
pinmap_pinout(rd, PinMap_CAN_RD);
pinmap_pinout(td, PinMap_CAN_TD);
can_reset(obj);
obj->dev->IER = 0; // Disable Interrupts
can_frequency(obj, 100000);
LPC_CANAF->AFMR = ACCF_BYPASS; // Bypass Filter
}
void can_free(can_t *obj) {
switch ((int)obj->dev) {
case CAN_1: LPC_SC->PCONP &= ~(1 << 13); break;
case CAN_2: LPC_SC->PCONP &= ~(1 << 14); break;
}
}
int can_frequency(can_t *obj, int f) {
int pclk = can_pclk(obj);
int btr = can_speed(SystemCoreClock, pclk, (unsigned int)f, 1);
if (btr > 0) {
uint32_t modmask = can_disable(obj);
obj->dev->BTR = btr;
obj->dev->MOD = modmask;
return 1;
} else {
return 0;
}
}
int can_write(can_t *obj, CAN_Message msg, int cc) {
unsigned int CANStatus;
CANMsg m;
can_enable(obj);
m.id = msg.id ;
m.dlc = msg.len & 0xF;
m.rtr = msg.type;
m.type = msg.format;
memcpy(m.data, msg.data, msg.len);
const unsigned int *buf = (const unsigned int *)&m;
CANStatus = obj->dev->SR;
if (CANStatus & 0x00000004) {
obj->dev->TFI1 = buf[0] & 0xC00F0000;
obj->dev->TID1 = buf[1];
obj->dev->TDA1 = buf[2];
obj->dev->TDB1 = buf[3];
if (cc) {
obj->dev->CMR = 0x30;
} else {
obj->dev->CMR = 0x21;
}
return 1;
} else if (CANStatus & 0x00000400) {
obj->dev->TFI2 = buf[0] & 0xC00F0000;
obj->dev->TID2 = buf[1];
obj->dev->TDA2 = buf[2];
obj->dev->TDB2 = buf[3];
if (cc) {
obj->dev->CMR = 0x50;
} else {
obj->dev->CMR = 0x41;
}
return 1;
} else if (CANStatus & 0x00040000) {
obj->dev->TFI3 = buf[0] & 0xC00F0000;
obj->dev->TID3 = buf[1];
obj->dev->TDA3 = buf[2];
obj->dev->TDB3 = buf[3];
if (cc) {
obj->dev->CMR = 0x90;
} else {
obj->dev->CMR = 0x81;
}
return 1;
}
return 0;
}
int can_read(can_t *obj, CAN_Message *msg, int handle) {
CANMsg x;
unsigned int *i = (unsigned int *)&x;
can_enable(obj);
if (obj->dev->GSR & 0x1) {
*i++ = obj->dev->RFS; // Frame
*i++ = obj->dev->RID; // ID
*i++ = obj->dev->RDA; // Data A
*i++ = obj->dev->RDB; // Data B
obj->dev->CMR = 0x04; // release receive buffer
msg->id = x.id;
msg->len = x.dlc;
msg->format = (x.type)? CANExtended : CANStandard;
msg->type = (x.rtr)? CANRemote: CANData;
memcpy(msg->data,x.data,x.dlc);
return 1;
}
return 0;
}
void can_reset(can_t *obj) {
can_disable(obj);
obj->dev->GSR = 0; // Reset error counter when CAN1MOD is in reset
}
unsigned char can_rderror(can_t *obj) {
return (obj->dev->GSR >> 16) & 0xFF;
}
unsigned char can_tderror(can_t *obj) {
return (obj->dev->GSR >> 24) & 0xFF;
}
void can_monitor(can_t *obj, int silent) {
uint32_t mod_mask = can_disable(obj);
if (silent) {
obj->dev->MOD |= (1 << 1);
} else {
obj->dev->MOD &= ~(1 << 1);
}
if (!(mod_mask & 1)) {
can_enable(obj);
}
}
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