mcp2515_bittime.h

00001 /******************************************************************************
00002  * 
00003  * Controller Area Network (CAN) Demo-Application
00004  * Atmel AVR with Microchip MCP2515 
00005  * 
00006  * Copyright (C) 2005 Martin THOMAS, Kaiserslautern, Germany
00007  * <eversmith@heizung-thomas.de>
00008  * http://www.siwawi.arubi.uni-kl.de/avr_projects
00009  *
00010  *****************************************************************************
00011  *
00012  * File    : mcp2515_bittime.h
00013  * Version : 0.9
00014  * 
00015  * Summary : MCP2515 CAN-timing values. Calculated with 
00016  *           a spreadsheet-based "Preprocessor" with information
00017  *           from the MCP2515 and AT90CAN128 datasheets.
00018  *
00019  *****************************************************************************/
00020 
00021 #include "mcp2515_defs.h"
00022 
00023 /*-----------------------*/
00024 /* global settings       */
00025 /*-----------------------*/
00026 
00027 /* CFG3 */
00028 
00029 // Start of Frame SOF (CLKOUT)
00030 // either SOF_ENABLE or SOF_DISABLE
00031 #define MCP_GENERAL_SOF (SOF_DISABLE)
00032 
00033 // Wake up Filter (WAKFIL)
00034 // either WAKFIL_ENABLE    or WAKFIL_DISABLE
00035 #define MCP_GENERAL_WAKFIL (WAKFIL_DISABLE)
00036 
00037 
00038 /*-----------------------*/
00039 /* 125 kBPS @ 4MHZ F_OSC */
00040 /*-----------------------*/
00041 
00042 /* CNF1 */
00043 
00044 // SJW as defined in mcp_defs.h
00045 // here: SJW = 1*TQ
00046 #define MCP_4MHz_125kBPS_SJW (SJW1)
00047 
00048 // Prescaler = (BRP+1)*2
00049 // here Prescaler = 4 -> BRP=1
00050 #define MCP_4MHz_125kBPS_BRP (1)
00051 
00052 
00053 /* CNF2 */
00054 
00055 // BLT-Mode defined in CNF3 (0 or BTLMODE from mcp_defs.h)
00056 #define MCP_4MHz_125kBPS_BLTMODE (BTLMODE)
00057 
00058 // 3 samples (SAMPLE_3X) or 1 sample (SAMPLE_1X)
00059 #define MCP_4MHz_125kBPS_SAM   (SAMPLE_1X)
00060 
00061 // (Phase Segment 1) PHSEG1 = PS1 - 1
00062 // here: PS1 calculated as 2 
00063 #define MCP_4MHz_125kBPS_PHSEG1 ((2-1)<<3)
00064 
00065 // (Propagation Delay) PRSEG = PRSEQTQ-1
00066 // here PRSEQTQ = 2
00067 #define MCP_4MHz_125kBPS_PRSEG (2-1)
00068 
00069 /* CNF3 */
00070 
00071 // (Phase Segment 2) PHSEG2 = PS2 - 1
00072 // here: PS2 calculated as 3
00073 #define MCP_4MHz_125kBPS_PHSEG (3-1)
00074 
00075 
00076 #define MCP_4MHz_125kBPS_CFG1 (MCP_4MHz_125kBPS_SJW | MCP_4MHz_125kBPS_BRP)
00077 #define MCP_4MHz_125kBPS_CFG2 (MCP_4MHz_125kBPS_BLTMODE | MCP_4MHz_125kBPS_SAM | MCP_4MHz_125kBPS_PHSEG1 | MCP_4MHz_125kBPS_PRSEG)
00078 #define MCP_4MHz_125kBPS_CFG3 (MCP_GENERAL_SOF | MCP_GENERAL_WAKFIL | MCP_4MHz_125kBPS_PHSEG)
00079 
00080 
00081 /*-----------------------*/
00082 /* 20 kBPS @ 4MHZ F_OSC  */
00083 /*-----------------------*/
00084 
00085 /* CNF1 */
00086 
00087 // SJW as defined in mcp_defs.h
00088 // here: SJW = 1*TQ
00089 #define MCP_4MHz_20kBPS_SJW (SJW1)
00090 
00091 // Prescaler = (BRP+1)*2
00092 // here Prescaler = 10 -> BRP=4  (20TQ)
00093 #define MCP_4MHz_20kBPS_BRP (4)
00094 
00095 
00096 /* CNF2 */
00097 
00098 // BLT-Mode defined in CNF3 (0 or BTLMODE from mcp_defs.h)
00099 #define MCP_4MHz_20kBPS_BLTMODE (BTLMODE)
00100 
00101 // 3 samples (SAMPLE_1X) or 1 sample (SAMPLE_1X)
00102 #define MCP_4MHz_20kBPS_SAM   (SAMPLE_1X)
00103 
00104 // (Phase Segment 1) PHSEG1 = PS1 - 1
00105 // here: PS1 calculated as 8
00106 #define MCP_4MHz_20kBPS_PHSEG1 ((8-1)<<3)
00107 
00108 // (Propagation Delay) PRSEG = PRSEQTQ-1
00109 // here PRSEQTQ = 3
00110 #define MCP_4MHz_20kBPS_PRSEG (3-1)
00111 
00112 /* CNF3 */
00113 
00114 // (Phase Segment 2) PHSEG2 = PS2 - 1
00115 // here: PS2 calculated as 8
00116 #define MCP_4MHz_20kBPS_PHSEG (8-1)
00117 
00118 
00119 #define MCP_4MHz_20kBPS_CFG1 (MCP_4MHz_20kBPS_SJW | MCP_4MHz_20kBPS_BRP)
00120 #define MCP_4MHz_20kBPS_CFG2 (MCP_4MHz_20kBPS_BLTMODE | MCP_4MHz_20kBPS_SAM | MCP_4MHz_20kBPS_PHSEG1 | MCP_4MHz_20kBPS_PRSEG)
00121 #define MCP_4MHz_20kBPS_CFG3 (MCP_GENERAL_SOF | MCP_GENERAL_WAKFIL | MCP_4MHz_20kBPS_PHSEG)