blob: a01555c589cb5c86ad4c4051bb7adce41a56cdc2 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
Hardware used
=============
* Saleae clone
* Olimex AT Mega32U4 "T" board
https://www.olimex.com/Products/Duino/AVR/AVR-T32U4/
For "high speed" operation, the T32U4 must be jumpered to run on 5V!
Software
========
* avr-gcc & companions
* ALSA
* LUFA
http://www.fourwalledcubicle.com/LUFA.php
in particular, the ClassDriver/AudioOutput demo
LUFA-140302/Demos/Device/ClassDriver/AudioOutput/
Adapted the Makefile:
14c14
< MCU = at90usb1287
---
> MCU = atmega32u4
16,17c16,17
< BOARD = USBKEY
< F_CPU = 8000000
---
> BOARD = OLIMEXT32U4
> F_CPU = 16000000
[make; avrdude ...]
Left channel on OC3A (pin32) -> Olimex "D5" -> probe 4.
Run "aplay -D front:CARD=Demo,DEV=0 /usr/share/sounds/alsa/test.wav"
while the Saleae records for 8 seconds. The result is pwmtest.sr.
Probe 5 was unterminated, see the crosstalk.
You can test the PWM decoder via CLI and extract the raw values:
sigrok-cli -i pwmtest.sr -P pwm:pwm=4 -B pwm=raw > PWM.raw
Add e.g. some .wav header using sox:
sox -t raw -e unsigned -b 8 -r 64000 PWM.raw PWM.wav
|
