2 layers17.3 × 30 mm Tac5, the printed circuit board in 3D

Tac5

CircuitPython support for TI's TAC5XXX audio codecs

Size: 17.3 × 30 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 14
Nets: 24
Pads: 89
Tracks, vias: 171, 41
Pours: 1
Routed: Yes
KiCad: KiCad 8.0 (file 20240108)
Created: 26 Aug 2024
Updated: 27 Jan 2025

Overview

Tac5 is an open-source printed circuit board by timchinowsky, from the timchinowsky/tac5 repository on GitHub, published under the MIT licence. It is a 2-layer board of 17.3 × 30 mm with 14 parts on 24 nets, routed with 171 tracks and 41 vias.

Its parts include 7 capacitors, 4 resistors, 2 connectors and 1 IC. It belongs with the audio and music boards of this library.

README

README.md

tac5

This repo describes PCBs and rp2040/rp2350 CircuitPython support for TI's TAC5xxx audio codecs. This code depends on extensions to CircuitPython's rp2pio library found in https://github.com/adafruit/circuitpython/pull/9659.

pcm.py uses the rp2 PIO to implement a PCM interface to the TAC5 which supports arbitrary numbers of channels, word sizes, and sample rates.
tac5.py implements a TAC5 class which knows how to initialize the TAC5xxx over I2C, write to its DACs, and read from its ADCs.
If multiple TAC5xxx parts with different I2C addresses are present, they are assumed to be wired in parallel for multichannel operation and configured appropriately. In this mode, each chip uses one time slot in the DOUT signal and makes its DOUT Hi-Z at other times.
Chips are mounted on breakout boards. KiCad files for these boards are here. Schematic and layout look like this:

Playing multichannel audio files

If you have speakers attached to the codecs, multi-track audio files stored on an SD card accessible to the rp2040 can be played on the codecs as follows:

python

Adafruit CircuitPython 9.1.0-beta.3-252-g10dfea4284-dirty on 2024-11-07; Adafruit Feather RP2040 with rp2040
>>> import tac5
>>> t=tac5.TAC5()
>>> t.play('/count_8ch_32bit_16000Hz.raw')
playing...
opening /count_8ch_32bit_16000Hz.raw ...
repeating...
repeating...
repeating...
...

Codec test, analog loopback

In this example, 4 TAC5212's are connected with BCLK, FSYNC, DOUT, DIN, SCL, and SDA in parallel, and on each chip, the differential DAC outputs are connected to the differential ADC inputs to provide test signals for the ADCs, i.e. OUT1P -> IN1P, OUT1M -> IN1M, OUT2P -> IN2P, OUT2M -> IN2M.

python

Adafruit CircuitPython 9.1.0-beta.3-76-g2f62612186-dirty on 2024-07-18; Adafruit Feather RP2040 with rp2040
>>> 
>>> import tac5
>>> t = tac5.TAC5()
>>> t.play()
playing...
>>> t.record()
sample,record0,record1,record2,record3,record4,record5,record6,record7,
0,-1,-1,-1,-1,-21642,13829,-311,-14878,
1,22355,-20880,-14861,22749,-19762,8760,6829,-20253,
2,21608,-13819,-15930,23037,-17183,3144,13306,-22783,
3,18190,-3347,-16936,22962,-13994,-2666,18482,-22111,
4,10858,7951,-17876,22524,-10311,-8313,21849,-18332,
5,602,17291,-18745,21730,-6263,-13440,23074,-11979,
6,-8849,22352,-19541,20593,-1995,-17725,22040,-3945,
7,-17070,21881,-20257,19131,2341,-20896,18845,4634,
8,-21748,15993,-20896,17368,6597,-22754,13806,12577,
9,-22490,6149,-21452,15331,10620,-23182,7417,18743,
...(115 more lines)

When called without arguments, play() creates test output (right now sine waves of various frequencies separated by gaps) for each DAC channel and sets up the interface to repeatedly send the data to the DACs in the background. When record() is called without arguments, it creates a buffer the same size as the playing buffer, fills it with ADC samples, and prints out the returned data in CSV format. The table below compares the DAC outputs as seen on a scope with the ADC outputs plotted on a spreadsheet:

DAC output		ADC output

Digital loopback test, no codec, single buffered

This example shows how a loopback test can be used to test streaming data transfer when if a codec is not present. Connect DOUT to DIN.

python

Adafruit CircuitPython 9.1.0-beta.0-426-g65556b42a5 on 2025-01-27; Adafruit Feather RP2350 with rp2350a
>>> 
>>> import tac5
>>> t = tac5.TAC5(channels=2, width=8, sample_rate=12000, address=None)
>>> t.rec(length=10)
recording...
>>> t.play(length=10, init='count')
playing...
>>> t.show(t.record_loop_buffer)
'sample'; 'ch0'; 'ch1'
0; -10; -9
1; -7; -6
2; -5; -4
3; -4; -3
4; -2; -1
5; 1; 2
6; 2; 3
7; 4; 5
8; 7; 8
9; 9; 10
>>> t.show(t.play_loop_buffer, shift=False)
'sample'; 'ch0'; 'ch1'
0; -10; -9
1; -8; -7

Digital loopback test, no codec, double buffered

Note that the count test data generated by tac5 is offset by 1 in play_loop2_buffer to distinguish it from the other buffer's data.

python

Adafruit CircuitPython 9.1.0-beta.0-426-g65556b42a5 on 2025-01-27; Adafruit Feather RP2350 with rp2350a
>>> 
>>> import tac5
>>> t = tac5.TAC5(channels=2, width=8, sample_rate=12000, address=None)
>>> t.rec(length=10, double_buffer=True)
recording...
>>> t.play(length=10, init='count', double_buffer=True)
playing...
>>> t.show(t.record_loop_buffer)
'sample'; 'ch0'; 'ch1'
0; -10; -9
1; -8; -7
2; -6; -5
3; -4; -3
4; -2; -1
5; 0; 1
6; 2; 3
7; 4; 5
8; 6; 7
9; 8; 9
>>> t.show(t.record_loop2_buffer)
'sample'; 'ch0'; 'ch1'
0; -9; -8
1; -7; -6

Digital loopback test, no codec, double buffered, recording to "tape"

python

Adafruit CircuitPython 9.1.0-beta.3-180-geda524f85c-dirty on 2024-10-24; Adafruit Feather RP2040 with rp2040
>>> import tac5
>>> t = tac5.TAC5(channels=2, width=8, sample_rate=12000, address=None)
>>> t.rec(length=10, double_buffer=True)
recording...
>>> t.play(length=10, test='count', double_buffer=True)
playing...
>>> t.show(t.record_loop_buffer)
'sample'; 'ch0'; 'ch1'
0; -9; -8
1; -7; -6
2; -5; -4
3; -3; -2
4; -1; 0
5; 1; 2
6; 3; 4
7; 5; 6
8; 7; 8
9; 9; 10
>>> t.tape('/foo.txt')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "tac5.py", line 347, in tape
KeyboardInterrupt:

Category and platform

Audio and music

Project files

Show this board on your page

https://pcbkit.io/boards/timchinowsky/tac5

The board's own page, for a message or a post.

Source

Repository: timchinowsky/tac5
Board file: pcb/tac5/tac5.kicad_pcb
Commit: 215e5b8
Licence: MIT

Parts

Qty	Value	Footprint	References
4	R_US	Resistor_SMD:R_0603_1608Metric	R1, R2, R3, R4
3	0.1uF	Capacitor_SMD:C_0603_1608Metric	C4, C6, C7
3	10uF	Capacitor_SMD:C_0603_1608Metric	C1, C3, C5
2	Conn_01x12	Connector_PinHeader_2.54mm:PinHeader_1x12_P2.54mm_Vertical	J1, J2
1	1uF	Capacitor_SMD:C_0603_1608Metric	C2
1	TAC5212	...timc:VQFN-24-1EP_4x4mm_P0.5mm_EP2.45x2.45mm_ThermalVias	U1

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Questions

How big is the Tac5 PCB?

It measures 17.3 × 30 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Tac5 use?

14 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Tac5 KiCad files?

From the timchinowsky/tac5 repository on GitHub, at the commit this page was made from: the board is pcb/tac5/tac5.kicad_pcb and its schematic pcb/tac5/tac5.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Tac5 design in my own project?

Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).