This commit is contained in:
Wolfgang Hottgenroth 2024-06-03 15:31:06 +02:00
parent 72b36d5a08
commit 9cf2ca6453
Signed by: wn
GPG Key ID: 836E9E1192A6B132
3 changed files with 75 additions and 3 deletions

64
docs/calc-76489an.py Normal file
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@ -0,0 +1,64 @@
N = 3579545.0
factor = 1.0594631
base = 440.0
frequencies = []
BEFORE_A = 46
f = base
for i in range (BEFORE_A):
idx = BEFORE_A - i - 1
print(f"{idx}: {f}")
frequencies.append(f)
f = base / factor
base = f
frequencies.reverse()
AFTER_A = 50
base = 440.0
for i in range(AFTER_A):
idx = BEFORE_A + i
f = base * factor
print(f"{idx}: {f}")
frequencies.append(f)
base = f
# print(f"{frequencies}")
codes = []
for i in range(len(frequencies)):
codes.append(round(N / (32.0 * frequencies[i])))
#const uint16_t frequencyCodes[8][12] = {
# // C, Cis, D, Dis, E, F, Fis, G, Gis, A, Ais, H
# { 06535, 06234, 05747, 05474, 05233, 05002, 04563, 04353, 04153, 03762, 03600, 03424 }, // Octave 1
# { 03256, 03116, 02764, 02636, 02515, 02401, 02271, 02165, 02065, 01771, 01700, 01612 }, // Octave 2
# { 01527, 01447, 01372, 01317, 01247, 01201, 01135, 01073, 01033, 00774, 00740, 00705 }, // Octave 3
# { 00654, 00624, 00575, 00550, 00523, 00500, 00456, 00435, 00415, 00376, 00360, 00342 }, // Octave 4
# { 00326, 00312, 00276, 00264, 00252, 00240, 00227, 00217, 00207, 00177, 00170, 00161 }, // Octave 5
# { 00153, 00145, 00137, 00132, 00125, 00120, 00114, 00107, 00103, 00100, 00074, 00071 }, // Octave 6
# { 00065, 00062, 00060, 00055, 00052, 00050, 00046, 00044, 00042, 00040, 00036, 00034 }, // Octave 7
# { 00033, 00031, 00030, 00026, 00025, 00024, 00023, 00022, 00021, 00020, 00017, 00016 } // Octave 8
#};
print("const uint16_t frequencyCodes[8][12] = {")
step = 12
for i in range(len(codes)):
if (i % step == 0):
print(" { ", end='')
print(f"{codes[i]}", end='')
if ((i+1) % step != 0):
print(", ", end='')
if ((i+1) % step == 0):
print(" }", end='')
if ((i+1) != len(codes)):
print(", ")
else:
print()
print("};")

12
psg.c
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@ -6,6 +6,8 @@
#include "scheduler.h" #include "scheduler.h"
const uint32_t BASE_FREQUENCY = 3579545;
// based on 3.579545 MHz // based on 3.579545 MHz
const uint16_t frequencyCodes[8][12] = { const uint16_t frequencyCodes[8][12] = {
{ 3420, 3229, 3047, 2876, 2715, 2562, 2419, 2283, 2155, 2034, 1920, 1812 }, { 3420, 3229, 3047, 2876, 2715, 2562, 2419, 2283, 2155, 2034, 1920, 1812 },
@ -76,7 +78,7 @@ inline static void WRITE_CYCLE(uint8_t chipNo) {
// WRITE_CYCLE(chipNo); // WRITE_CYCLE(chipNo);
//} //}
static void psgWriteFrequency(uint8_t chip, uint8_t channel, uint16_t frequencyCode) { static void psgWriteFrequencyCode(uint8_t chip, uint8_t channel, uint16_t frequencyCode) {
uint8_t chipNo = chip; uint8_t chipNo = chip;
uint8_t regAddr = (channel % 3) * 2; uint8_t regAddr = (channel % 3) * 2;
@ -132,10 +134,16 @@ void psgPlayTone(uint8_t chip, uint8_t channel, uint8_t volume, t_octave octave,
psgAmplitude(chip, channel, 0); psgAmplitude(chip, channel, 0);
} else { } else {
psgAmplitude(chip, channel, volume); psgAmplitude(chip, channel, volume);
psgWriteFrequency(chip, channel, frequencyCodes[octave][note]); psgWriteFrequencyCode(chip, channel, frequencyCodes[octave][note]);
} }
} }
void psgPlayFrequency(uint8_t chip, uint8_t channel, uint8_t volume, uint16_t frequency) {
uint16_t frequencyCode = BASE_FREQUENCY / (32 * frequency);
psgAmplitude(chip, channel, volume);
psgWriteFrequencyCode(chip, channel, frequencyCode);
}
void psgInit() { void psgInit() {
// address/data bus // address/data bus
P2DIR = 0xff; P2DIR = 0xff;

2
psg.h
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@ -41,6 +41,6 @@ void psgInit();
void psgPlayTone(uint8_t chip, uint8_t channel, uint8_t volume, t_octave octave, t_note note); void psgPlayTone(uint8_t chip, uint8_t channel, uint8_t volume, t_octave octave, t_note note);
void psgAmplitude(uint8_t chip, uint8_t channel, uint8_t volume); void psgAmplitude(uint8_t chip, uint8_t channel, uint8_t volume);
void psgPlayFrequency(uint8_t chip, uint8_t channel, uint8_t volume, uint16_t frequency);
#endif // _PSG_H_ #endif // _PSG_H_