After a year of waiting I added some new things to AccessB design:
- Changed the USB port from mini to micro
- Added another micro USB port only for powering the board, this if I want to connect a cellphone to the AccessB and a wall charger.
- Added an extra pin to ICSP port to match the six pin of the PicKit 3
I sent the KiCAD gerber files to PCBWAY and I received this:
With the boards on my hands I see one mistake: the footprint for the PIC18F2550 was the wrong size, the PIC uses SOIC28 footprint same as the I used on the design so what's wrong??? look at this:
The PIC uses the Wider version of SOIC28 and I used the Narrow version (I forgot to print the PCB design and check if all parts fit ok) , the solution was easy: convert the SOIC28 Wide to SOIC-SOJ28 and all the PIC pins fit the footprints pads, with C3 too close but not a problem:
The next step was solder and test the power supply for the voltage level selection part of the voltage level shifter, it output 0.8/1.2/1.8/2.5/3.3 volts without problems, the only down was that MCP1603 ADJI don't support the changue on the fly of the bottom voltage divisor to changue the output, If you do it magick smoke from MCP1603 ADJI comes out, I must dissconnect the board from the USB port and then changue the pin jumper to the voltage ouput that I want and then recconect, I don't know why and I read the datasheet and the evaluation board manual from where I take the design of the power supply and it doesn't mention anything about. I can't check the variable output because I don't have at hand any pot.
Finally this is the board with almost all soldered:
Finally I inserted the PicKit 3 on the ISCP port and I see another problem, the capacitor C3 get in the way of the PicKit 3:
Anyway the AccessB PIC was programmed without problems and was enumerated by the USB por of my laptop and detected by my test software, the next steps will be:
- Check if AccessB Voltage Level Shifter Works and communicate with a SPI/I2C Devices at 3.3/2.5/1.8/1.2/0.8 volts.
- Change the SOIC28 Narrow to Wide.
- Change the position of C3.
- Point out on the silk screen that P5 (USB micro port) is used only for power and P2 for data and power.
- Update the Hackaday.io project
So there is some work to do, see you on the next days.
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