CAN 比特率和采样点计算

目前 CAN 架构根据输入频率和比特率自动计算。采样点的规则按照 CIA 标准协议

/* Use CiA recommended sample points */
if (bt->sample_point) {
sample_point_nominal = bt->sample_point;
} else {
if (bt->bitrate > 800000)
sample_point_nominal = 750;
else if (bt->bitrate > 500000)
sample_point_nominal = 800;
else
sample_point_nominal = 875;
}

比特率计算公式（详细原理可以百度，这里只介绍芯片配置相关）：

BitRate = clk_can / (2 *(brq + 1) / ((tseg2 + 1) + (tseg1 + 1) + 1)

Sample = (1 + (tseg1 + 1)) / (1 + (tseg1 + 1) &#