Differences

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--- projects:sand_drawing:work_logs:further_electronics [2020/05/26 11:57] – created tjhowse
+++ projects:sand_drawing:work_logs:further_electronics [2020/05/26 12:14] – tjhowse
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-{{indexmenu_n>8}}
+{{indexmenu_n>9}}
 ====== What I want to accomplish ======
-  * Do the electronics
+  * Design the PCB
 ====== What I've done ======
+=== Microcontroller ===
+I went back and forth on this a few times. There were two main choices to make:
+  * ESP8266, or
+  * ESP32
+and
+  * Breakout board, or
+  * Implement directly.
+In my first [[projects:sand_drawing:work_logs:software|software work log]] I essentially decided on the ESP32. The ESP8266 was a bit cheaper, but it really doesn't have much overhead for me to work with. If I wanted to stick with micropython, which I did for other reasons, I would need to go up to the ESP32. I selected the ESP-WROOM-32D specifically.
+{{:projects:sand_drawing:work_logs:pasted:20200526-120518.png}}
+Breakout board vs bare.
+The next decision was around whether I wanted to design the PCB to accept a breakout board or the bare ESP-WROOM-32D package. The breakout board would be simpler, easier to solder, and provides a USB programming interface. The downside is that I couldn't find a consistently-available version of the board. Searching for "ESP32 breakout" or "ESP32 nodemcu" would yield a dozen slightly different boards. The Wimos D2 mini knockoff I was using earlier on in the project was more consistently knocked-off.
+I'd hate for someone to be ordering the bits to build one of these robots and end up with a breakout board that didn't fit, or had the wrong pinout. So I decided to go with the bare ESP-WROOM-32D module. I had to implement some pull-ups and buttons to put it into a flashing state, but overall it wasn't too difficult.
+=== Stepper drivers ===
+^ Driver ^ Cost ^ Microstepping ^ Silent ^ Note ^
+| A4988 | $ | 1/16 | No | Cheap and cheerful |
+| DRV8825 | $$ | 1/32 | No | Fragile |
+| TMC2100 | $$$ | 1/256?? | Potentially | Very fragile |