使用LUA小程序计算串口误差率和实际波特率
比如STM32H7的串口外设主频配置为100MHz。LUA代码：
BspArray =
{
110,
300,
600,
1200,
2400,
4800,
9600,
19200,
38400,
57600,
115200,
128000,
230400,
256000,
460800,
500000,
512000,
600000,
750000,
921600,
1000000,
1152000,
1500000,
2000000,
2500000,
3000000
}
Fclk = 100000000-- 用户设置串口外设主频
OVER8 = 0 -- 0表示16过采样，1表示8倍过采样
print("所需波特率 实际值波特率 误差 BRR寄存器数值")
for i=1, #BspArray, 1 do
Bsp = BspArray
if(OVER8 == 0) then
UARRTDIV = Fclk/Bsp
mantissa = (UARRTDIV + 0.5)//1
Bsp1 = Fclk/mantissa
str = string.format("%-13d %-13.4f %7.4f%% %-.4f = 0x%08x",
Bsp, Bsp1, (Bsp1-Bsp)/Bsp*100, mantissa, mantissa)
print(str)
else
UARRTDIV = 2*Fclk/Bsp
mantissa = (UARRTDIV + 0.5)//1
mantissa = mantissa & 0xfff0
fraction = mantissa & 0x0f
fraction = fraction >> 1
Bsp1 = 2*Fclk/(mantissa+fraction)
str = string.format("%-13d %-13.4f %7.4f%% %-.4f=0x%08x",
Bsp, Bsp1, (Bsp1-Bsp)/Bsp*100, mantissa+fraction, mantissa+fraction)
print(str)
end
end
16过采样的误差率和实际速度如下 :
所需波特率 实际值波特率 误差 BRR寄存器数值
110 110.0000 -0.0000% 909091.0000 = 0x000ddf23
300 300.0003 0.0001% 333333.0000 = 0x00051615
600 599.9988 -0.0002% 166667.0000 = 0x00028b0b
1200 1200.0048 0.0004% 83333.0000 = 0x00014585
2400 2399.9808 -0.0008% 41667.0000 = 0x0000a2c3
4800 4800.0768 0.0016% 20833.0000 = 0x00005161
9600 9599.6928 -0.0032% 10417.0000 = 0x000028b1
19200 19201.2289 0.0064% 5208.0000 = 0x00001458
38400 38402.4578 0.0064% 2604.0000 = 0x00000a2c
57600 57603.6866 0.0064% 1736.0000 = 0x000006c8
115200 115207.3733 0.0064% 868.0000 = 0x00000364
128000 128040.9731 0.0320% 781.0000 = 0x0000030d
230400 230414.7465 0.0064% 434.0000 = 0x000001b2
256000 255754.4757 -0.0959% 391.0000 = 0x00000187
460800 460829.4931 0.0064% 217.0000 = 0x000000d9
500000 500000.0000 0.0000% 200.0000 = 0x000000c8
512000 512820.5128 0.1603% 195.0000 = 0x000000c3
600000 598802.3952 -0.1996% 167.0000 = 0x000000a7
750000 751879.6992 0.2506% 133.0000 = 0x00000085
921600 917431.1927 -0.4523% 109.0000 = 0x0000006d
1000000 1000000.0000 0.0000% 100.0000 = 0x00000064
1152000 1149425.2874-0.2235% 87.0000 = 0x00000057
1500000 1492537.3134-0.4975% 67.0000 = 0x00000043
2000000 2000000.0000 0.0000% 50.0000 = 0x00000032
2500000 2500000.0000 0.0000% 40.0000 = 0x00000028
3000000 3030303.0303 1.0101% 33.0000 = 0x00000021
https://img.anfulai.cn/dz/attachment/forum/202311/11/003808fflwl3o839vf923o.png
8过采样的误差率和实际速度如下 :
所需波特率 实际值波特率 误差 BRR寄存器数值
110 4106.4389 3633.1263% 48704.0000=0x0000be40
300 17705.3824 5801.7941% 11296.0000=0x00002c20
600 35410.7649 5801.7941% 5648.0000=0x00001610
1200 5620.5036 368.3753% 35584.0000=0x00008b00
2400 11241.0072 368.3753% 17792.0000=0x00004580
4800 4800.3072 0.0064% 41664.0000=0x0000a2c0
9600 9600.6144 0.0064% 20832.0000=0x00005160
19200 19201.2289 0.0064% 10416.0000=0x000028b0
38400 38461.5385 0.1603% 5200.0000=0x00001450
57600 57603.6866 0.0064% 3472.0000=0x00000d90
115200 115740.7407 0.4694% 1728.0000=0x000006c0
128000 128865.9794 0.6765% 1552.0000=0x00000610
230400 231481.4815 0.4694% 864.0000=0x00000360
256000 260416.6667 1.7253% 768.0000=0x00000300
460800 462962.9630 0.4694% 432.0000=0x000001b0
500000 500000.0000 0.0000% 400.0000=0x00000190
512000 520833.3333 1.7253% 384.0000=0x00000180
600000 625000.0000 4.1667% 320.0000=0x00000140
750000 781250.0000 4.1667% 256.0000=0x00000100
921600 961538.4615 4.3336% 208.0000=0x000000d0
1000000 1041666.6667 4.1667% 192.0000=0x000000c0
1152000 1250000.0000 8.5069% 160.0000=0x000000a0
1500000 1562500.0000 4.1667% 128.0000=0x00000080
2000000 2083333.3333 4.1667% 96.0000=0x00000060
2500000 2500000.0000 0.0000% 80.0000=0x00000050
3000000 3125000.0000 4.1667% 64.0000=0x00000040
https://img.anfulai.cn/dz/attachment/forum/202311/11/003927eqp0qq0fu0qyevzc.png
同样的方法，STM32F4的串口主频84MHz时测试。
LUA代码和STM32H7的代码不同：
BspArray =
{
110,
300,
600,
1200,
2400,
4800,
9600,
19200,
38400,
57600,
115200,
128000,
230400,
256000,
460800,
500000,
512000,
600000,
750000,
921600,
1000000,
1152000,
1500000,
2000000,
2500000,
3000000
}
Fclk = 84000000-- 用户设置串口外设主频
OVER8 = 0 -- 0表示16过采样，1表示8倍过采样
print("所需波特率 实际值波特率 误差 BRR寄存器数值")
for i=1, #BspArray, 1 do
Bsp = BspArray
UARRTDIV = Fclk/(8*(2-OVER8))/Bsp
mantissa = UARRTDIV//1
fraction = UARRTDIV - mantissa
if(OVER8 == 0) then
fraction_adj = (fraction*16 + 0.5)//1
if(fraction_adj > 16) then
fraction_adj = 0
mantissa = mantissa + 1
end
Bsp1 = Fclk/(8*(2-OVER8))/(mantissa+ fraction_adj/16)
str = string.format("%-13d %-13.4f %7.4f%% %-.4f = 0x%08x",
Bsp, Bsp1, (Bsp1-Bsp)/Bsp*100, mantissa+fraction_adj/16, mantissa*16+fraction_adj)
print(str)
else
fraction_adj = (fraction*8 + 0.5)//1
if(fraction_adj > 8) then
fraction_adj = 0
mantissa = mantissa + 1
end
Bsp1 = Fclk/(8*(2-OVER8))/(mantissa+ fraction_adj/8)
str = string.format("%-13d %-13.4f %7.4f%% %-.4f=0x%08x",
Bsp, Bsp1, (Bsp1-Bsp)/Bsp*100, mantissa+fraction_adj/8, mantissa*16+fraction_adj)
print(str)
end
end
16过采样的误差率和实际速度如下 :
所需波特率 实际值波特率 误差 BRR寄存器数值
110 110.0001 0.0000% 47727.2500 = 0x000ba6f4
300 300.0000 0.0000% 17500.0000 = 0x000445c0
600 600.0000 0.0000% 8750.0000 = 0x000222e0
1200 1200.0000 0.0000% 4375.0000 = 0x00011170
2400 2400.0000 0.0000% 2187.5000 = 0x000088b8
4800 4800.0000 0.0000% 1093.7500 = 0x0000445c
9600 9600.0000 0.0000% 546.8750 = 0x0000222e
19200 19200.0000 0.0000% 273.4375 = 0x00001117
38400 38391.2249 -0.0229% 136.7500 = 0x0000088c
57600 57613.1687 0.0229% 91.1250 = 0x000005b2
115200 115226.3374 0.0229% 45.5625 = 0x000002d9
128000 128048.7805 0.0381% 41.0000 = 0x00000290
230400 230136.9863 -0.1142% 22.8125 = 0x0000016d
256000 256097.5610 0.0381% 20.5000 = 0x00000148
460800 461538.4615 0.1603% 11.3750 = 0x000000b6
500000 500000.0000 0.0000% 10.5000 = 0x000000a8
512000 512195.1220 0.0381% 10.2500 = 0x000000a4
600000 600000.0000 0.0000% 8.7500 = 0x0000008c
750000 750000.0000 0.0000% 7.0000 = 0x00000070
921600 923076.9231 0.1603% 5.6875 = 0x0000005b
1000000 1000000.0000 0.0000% 5.2500 = 0x00000054
1152000 1150684.9315-0.1142% 4.5625 = 0x00000049
1500000 1500000.0000 0.0000% 3.5000 = 0x00000038
2000000 2000000.0000 0.0000% 2.6250 = 0x0000002a
2500000 2470588.2353-1.1765% 2.1250 = 0x00000022
3000000 3000000.0000 0.0000% 1.7500 = 0x0000001c
8过采样的误差率和实际速度如下 :
所需波特率 实际值波特率 误差 BRR寄存器数值
110 110.0001 0.0000% 95454.5000=0x00174de4
300 300.0000 0.0000% 35000.0000=0x00088b80
600 600.0000 0.0000% 17500.0000=0x000445c0
1200 1200.0000 0.0000% 8750.0000=0x000222e0
2400 2400.0000 0.0000% 4375.0000=0x00011170
4800 4800.0000 0.0000% 2187.5000=0x000088b4
9600 9600.0000 0.0000% 1093.7500=0x00004456
19200 19200.0000 0.0000% 546.8750=0x00002227
38400 38391.2249 -0.0229% 273.5000=0x00001114
57600 57613.1687 0.0229% 182.2500=0x00000b62
115200 115226.3374 0.0229% 91.1250=0x000005b1
128000 128048.7805 0.0381% 82.0000=0x00000520
230400 230136.9863 -0.1142% 45.6250=0x000002d5
256000 256097.5610 0.0381% 41.0000=0x00000290
460800 461538.4615 0.1603% 22.7500=0x00000166
500000 500000.0000 0.0000% 21.0000=0x00000150
512000 512195.1220 0.0381% 20.5000=0x00000144
600000 600000.0000 0.0000% 17.5000=0x00000114
750000 750000.0000 0.0000% 14.0000=0x000000e0
921600 923076.9231 0.1603% 11.3750=0x000000b3
1000000 1000000.0000 0.0000% 10.5000=0x000000a4
1152000 1150684.9315-0.1142% 9.1250=0x00000091
1500000 1500000.0000 0.0000% 7.0000=0x00000070
2000000 2000000.0000 0.0000% 5.2500=0x00000052
2500000 2470588.2353-1.1765% 4.2500=0x00000042
3000000 3000000.0000 0.0000% 3.5000=0x00000034
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