2013-10-18 Producing PCB with CNC machine (Raspberry Pi – IR&Temp daughterboard)

Using a K2 CNC machine to mill a printed circuit board.. also showing the finished board (stills and video) with soldered components at the end of the video. If bored…. skip ahead.

The circuit is a new version of my Raspberry PI Infrared emitter and temperature sensor microcontroller daughterboard. It was designed in CadSoft Eagle, the GCode for the CNC machine was created using the free online tool http://rapid-pcb.com, the CNC GCode was executed using Artsoft Mach3 and the microcontroller used is a Microchip PIC18F2550.

I don’t have any professional light sources so the video and still images of the PCB is not so great with the very bright reflection of the PCB copper messing up the shots. The quality of the milled PCB is really good, but it is difficult to show this in the video.

The CNC machine also drilled 0.9mm holes for the components. However I used a bigger manual drill on some of the holes to fit the bigger components. These holes are not so perfect as the holes created by the CNC machine. If I weren’t so lazy I should have used multiple drill passes with different diameter drill bits on the CNC machine. Also the biggest component, a TDK-Lambda DCDC converter, is also missing from the PCB so one of the corners of the PCB doesn’t look very good.

I am using the TRIM pin of the DCDC converter to output 5.1V instead of 5.0V and feed this directly to the Raspberry Pi GPIO header to prevent brownouts and compensate for fuses and other voltage-lowering components on the Pi. This has worked very well in the past.

The PIC18F2550 runs a custom firmware programmed in MPLab X/C8 that provides a command line serial UART interface communicating with the Raspberry Pi’s (GPIO) serial port. The CLI has commands for sending very large/long infrared signals (needed for some Daikin AC units) and reading the temperature sensor (Microchip MCP9701A). The temperature sensor and infrared emitter is connected using the 8-pin RJ-45 ports (external cables).

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Post time: Jun-16-2017
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