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I'm not bringing in the whole messy history - some of it exists in previous generations of the guitar pedal project, but most of it is just me making (and hopefully fixing) mistakes and random updates. So this is just the current state of the project. There are two core "modular" boards with the core hardware: - The rp2354 board contains the Raspberry Pi RP2354 microcontroller together with the required basic infrastructure: 12MHz crystal, bypass capacitors, and components for the internal 1.1V switching power supply of the rp2354. - the codec board contains TAC5112 stereo codec, and a small 2kbit EEPROM flash chip. Both of the core boards just have a Hirose BM28 connector on the back that carries 3.3V power and exposes most of the core capabilities of the chips. The reason for these boards is purely so that I could test out different form factors without having to always redo the codec and MCU. The BM28 connector is tiny - quite arguably inconveniently so - but meant that I could fit those modular boards in fairly arbitrary footprints. End result: I could make tons of throw-away single-sided test boards to see what worked, while re-using the more complex core modules. So in addition to the two core modules, there are two "carrier" boards that then are the actual final - at least for now - form factor: - The "audio-jacks" board is the analog board that houses the audio jacks, the 9V DC power jack, and the high-impedance input buffering to the TAC5112 codec board. - The "pedal-board" contains the digital side - aside from the rp2354 board it has the rotary encoders, the Qwiic connector for i2c to the display module, activity LEDs and a pin header for the two stomp switches. The digital board also has the USB-C connector for programming. The carrier boards share a 5V incoming power rail, either fed from the 9V DC jack (another low-noise linear regulator - I didn't want a noisy switching regulator anywhere near the analog board) or from the USB-C connector. They then independently regulate that 5V supply down to 3.3V for their respective core modules. The carrier boards are connected with a 12p FFC cable that carries the 5V power supply and the 3.3V digital signals (i2c for control, i2s for audio). Note that while the TAC5112 is a stereo codec, and both channels are brought out on the BM28 connector, the the audio jack board is completely mono and so only one of the channels is actually used. Al the boards are 4-layer boards: only the rp2354 really needs it, but I just standardized on it and the cost difference is negligible. If you want to make your own version of the hardware, I'd suggest using one of the commercial rp2350 based boards, and just putting the TAC5112 directly on the audio jack board. Because the whole "modular board" thing really was only for flexibility of design. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
5 lines
116 B
Plaintext
5 lines
116 B
Plaintext
(fp_lib_table
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(lib (name "Mylib")(type "KiCad")(uri "${KIPRJMOD}/symbols")(options "")(descr ""))
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