seeed_can_spi.cpp

00001 /* seeed_can_spi.cpp
00002  * Copyright (c) 2013 Sophie Dexter
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016  
00017 #include "seeed_can_spi.h"
00018 
00019 /** reset the MCP2515
00020  */
00021 void mcpReset(mcp_can_t *obj)
00022 {
00023     obj->ncs = 0;
00024     obj->spi.write(MCP_RESET);
00025     obj->ncs = 1;
00026     wait_ms(10);
00027 }
00028 
00029 /** read from a single MCP2515 register
00030  */
00031 uint8_t mcpRead(mcp_can_t *obj, const uint8_t address)
00032 {
00033     uint8_t result;
00034 
00035     obj->ncs = 0;
00036     obj->spi.write(MCP_READ);
00037     obj->spi.write(address);
00038     result = obj->spi.write(0x00);
00039     obj->ncs = 1;
00040     return result;
00041 }
00042 
00043 /** read multiple MCP2515 registers sequentially into an array (relies on address auto-increment)
00044  */
00045 void mcpReadMultiple(mcp_can_t *obj, const uint8_t address, uint8_t values[], const uint8_t n)
00046 {
00047     obj->ncs = 0;
00048     obj->spi.write(MCP_READ);
00049     obj->spi.write(address);
00050     for (uint32_t i=0; i<n; i++) {
00051         values[i] = obj->spi.write(0x00);
00052     }
00053     obj->ncs = 1;
00054 }
00055 
00056 /** read the specified MCP2515 receive buffer into an array (needs one fewer SPI transfer than mcpReadMultiple)
00057  */
00058 void mcpReadBuffer(mcp_can_t *obj, const uint8_t command, uint8_t values[], const uint8_t n)
00059 {
00060     obj->ncs = 0;
00061     obj->spi.write(command);
00062     for (uint32_t i=0; i<n; i++) {
00063         values[i] = obj->spi.write(0x00);
00064     }
00065     obj->ncs = 1;
00066 }
00067 
00068 /**  write to a single MCP2515 register
00069  */
00070 void mcpWrite(mcp_can_t *obj, const uint8_t address, const uint8_t value)
00071 {
00072     obj->ncs = 0;
00073     obj->spi.write(MCP_WRITE);
00074     obj->spi.write(address);
00075     obj->spi.write(value);
00076     obj->ncs = 1;
00077 }
00078 
00079 /** write to multiple MCP2515 registers consecutively from an array
00080  */
00081 void mcpWriteMultiple(mcp_can_t *obj, const uint8_t address, const uint8_t values[], const uint8_t n)
00082 {
00083     obj->ncs = 0;
00084     obj->spi.write(MCP_WRITE);
00085     obj->spi.write(address);
00086     for (uint32_t i=0; i<n; i++) {
00087         obj->spi.write(values[i]);
00088     }
00089     obj->ncs = 1;
00090 }
00091 
00092 /** write to the specified MCP2515 transmit buffer from an array (needs one fewer SPI transfer than mcpWriteMultiple)
00093  */
00094 void mcpWriteBuffer(mcp_can_t *obj, const uint8_t command, uint8_t values[], const uint8_t n)
00095 {
00096     obj->ncs = 0;
00097     obj->spi.write(command);
00098     for (uint32_t i=0; i<n; i++) {
00099         obj->spi.write(values[i]);
00100     }
00101     obj->ncs = 1;
00102 }
00103 
00104 /** initiate transmission of the specified MCP2515 transmit buffer
00105  */
00106 void mcpBufferRTS(mcp_can_t *obj, const uint8_t command)
00107 {
00108     obj->ncs = 0;
00109     obj->spi.write(command);
00110     obj->ncs = 1;
00111 }
00112 
00113 /**  read mcp2515's status register
00114  */
00115 uint8_t mcpStatus(mcp_can_t *obj)
00116 {
00117     uint8_t status;
00118 
00119     obj->ncs = 0;
00120     obj->spi.write(MCP_READ_STATUS);
00121     status = obj->spi.write(0x00);
00122     obj->ncs = 1;
00123     return status;
00124 }
00125 
00126 /**  read mcp2515's receive status register
00127  */
00128 uint8_t mcpReceiveStatus(mcp_can_t *obj)
00129 {
00130     uint8_t status;
00131 
00132     obj->ncs = 0;
00133     obj->spi.write(MCP_RX_STATUS);
00134     status = obj->spi.write(0x00);
00135     obj->ncs = 1;
00136     return status;
00137 }
00138 
00139 /** modify bits of a register specified by a mask
00140  */
00141 void mcpBitModify(mcp_can_t *obj, const uint8_t address, const uint8_t mask, const uint8_t data)
00142 {
00143     obj->ncs = 0;
00144     obj->spi.write(MCP_BITMOD);
00145     obj->spi.write(address);
00146     obj->spi.write(mask);
00147     obj->spi.write(data);
00148     obj->ncs = 1;
00149 }