Skip to content

Fix frequency offset for AVR #202

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
tomcombriat merged 4 commits into from
Oct 24, 2023
Merged

Fix frequency offset for AVR #202

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
44191d1
Fix frequency offset for AVR
tomcombriat Oct 10, 2023
cb309ef
Improved readability
tomcombriat Oct 14, 2023
b05d20e
Improved readability
tomcombriat Oct 14, 2023
523ba59
Merge branch 'AVR_misFreq' of github.com:tomcombriat/Mozzi into bugfi…
tomcombriat Oct 24, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
18 changes: 14 additions & 4 deletions MozziGuts_impl_AVR.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -168,7 +168,11 @@ static uint8_t mozzi_TCCR4A, mozzi_TCCR4B, mozzi_TCCR4C, mozzi_TCCR4D,
static void startAudio() {
backupPreMozziTimer1();
Timer1.initializeCPUCycles(
F_CPU / AUDIO_RATE,
(F_CPU/AUDIO_RATE)-1, // the -1 here is a result of empirical tests
// that showed that it brings the resulting frequency
// closer to what is expected.
// see: https://github.com/sensorium/Mozzi/pull/202

PHASE_FREQ_CORRECT); // set period, phase and frequency correct
TIMSK1 = _BV(TOIE1); // Overflow Interrupt Enable (when not using
// Timer1.attachInterrupt())
Expand Down Expand Up @@ -198,10 +202,16 @@ static void startAudio() {
// pinMode(AUDIO_CHANNEL_2_PIN, OUTPUT); // set pin to output for audio
# if (AUDIO_MODE == STANDARD)
Timer1.initializeCPUCycles(
F_CPU / AUDIO_RATE,
(F_CPU/AUDIO_RATE)-1,// the -1 here is a result of empirical tests
// that showed that it brings the resulting frequency
// closer to what is expected.
// see: https://github.com/sensorium/Mozzi/pull/202
PHASE_FREQ_CORRECT); // set period, phase and frequency correct
# else // (AUDIO_MODE == STANDARD_PLUS)
Timer1.initializeCPUCycles(F_CPU / PWM_RATE,
Timer1.initializeCPUCycles((F_CPU/PWM_RATE)-1, // the -1 here is a result of empirical tests
// that showed that it brings the resulting frequency
// closer to what is expected.
// see: https://github.com/sensorium/Mozzi/pull/202
FAST); // fast mode enables higher PWM rate
# endif
Timer1.pwm(AUDIO_CHANNEL_1_PIN,
Expand Down Expand Up @@ -267,7 +277,7 @@ static void startAudio() {
pinMode(AUDIO_CHANNEL_1_lowByte_PIN,
OUTPUT); // set pin to output for audio, use 499k resistor
Timer1.initializeCPUCycles(
F_CPU / 125000,
F_CPU/125000,
FAST); // set period for 125000 Hz fast pwm carrier frequency = 14 bits
Timer1.pwm(AUDIO_CHANNEL_1_highByte_PIN,
0); // pwm pin, 0% duty cycle, ie. 0 signal
Expand Down