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[NUC472] Fix SetBaudRate 5% inaccuracy issue

pull/3104/head
cyliangtw 2016-10-21 14:01:17 +08:00
parent ae12346b8e
commit 85c45a5174
1 changed files with 20 additions and 0 deletions
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20
targets/TARGET_NUVOTON/TARGET_NUC472/device/StdDriver/nuc472_can.c
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@ -419,6 +419,7 @@ uint32_t CAN_SetBaudRate(CAN_T *tCAN, uint32_t u32BaudRate)
SystemCoreClockUpdate();
#if 0 // original implementation got 5% inaccuracy.
u32Value = SystemCoreClock;
if(u32BaudRate * 8 < (u32Value/2)) {
@ -428,7 +429,26 @@ uint32_t CAN_SetBaudRate(CAN_T *tCAN, uint32_t u32BaudRate)
u8Tseg1 = 2;
u8Tseg2 = 1;
}
#else
u32Value = SystemCoreClock / u32BaudRate;
/* Fix for most standard baud rates, include 125K */
u8Tseg1 = 3;
u8Tseg2 = 2;
while(1)
{
if(((u32Value % (u8Tseg1 + u8Tseg2 + 3)) == 0) | (u8Tseg1 >= 15))
break;
u8Tseg1++;
if((u32Value % (u8Tseg1 + u8Tseg2 + 3)) == 0)
break;
if(u8Tseg2 < 7)
u8Tseg2++;
}
#endif
u32Brp = SystemCoreClock/(u32BaudRate) / (u8Tseg1 + u8Tseg2 + 3) -1;
u32Value = ((uint32_t)u8Tseg2 << CAN_BTIME_TSEG2_Pos) | ((uint32_t)u8Tseg1 << CAN_BTIME_TSEG1_Pos) |