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Add rounding to baud rate calculation

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Without rounding:
- Divisor: 33 = (125000000 / 115200 / 32)
- RCAP2 value: 65503
- Actual baud rate: 118371 = (125000000 / 32 / 33)
- Error: 2.75%

With rounding:
- Divisor: 34 = ((125000000 / 115200 + 16) / 32)
- RCAP2 value: 65502
- Actual baud rate: 114889 = (125000000 / 32 / 34)
- Error: 0.27%

Should fix https://github.com/logicog/RTLPlayground/issues/48
This commit is contained in:
Tobias Diedrich
2025-12-22 23:28:50 +01:00
committed by logicog
parent ed62e46790
commit 6441e85752
1 changed files with 2 additions and 2 deletions
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rtlplayground.c
+2 -2
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@@ -1649,8 +1649,8 @@ void setup_serial(void)
// The RCAP2 registers contain the high/low byte that is loaded into // The RCAP2 registers contain the high/low byte that is loaded into
// timer2 when T2 overflows to 0x10000 // timer2 when T2 overflows to 0x10000
RCAP2H = (0x10000 - (CLOCK_HZ / SERIAL_BAUD_RATE / 32)) >> 8; RCAP2H = (0x10000 - ((CLOCK_HZ / SERIAL_BAUD_RATE + 16) / 32)) >> 8;
RCAP2L = (0x10000 - (CLOCK_HZ / SERIAL_BAUD_RATE / 32)) % 0xff; RCAP2L = (0x10000 - ((CLOCK_HZ / SERIAL_BAUD_RATE + 16) / 32)) % 0xff;
PCON |= 0x80; // Double the Baud Rate PCON |= 0x80; // Double the Baud Rate