Author Topic: Problem with re-programming RFduino on Custom board  (Read 1410 times)

hughanderson

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Problem with re-programming RFduino on Custom board
« on: January 12, 2015, 01:38:40 AM »
Hi,

I have developed a custom board for the RFduino, which provides some I2C based I/O, and uses a CP2103 for the USB/UART. The board seemed to be working fine, allowing me to upload small test applications to the RFduino. However, once I loaded the  MPU6050 orientation demo to the board (which incidentally works beautifully), I can no longer program the board. The impression I have is that perhaps some aspect of the high data rate (lots of 115200 baud data), or the short pause after a reset, or some other effect is preventing further programming.

When I attempt to program it, I can see the reset line going low then high, and  almost immediately I get the dreaded message
   get
   fail........ fail....... fail .......

I wondered if there was some timing diagram that could tell me the timing constraints on the DTR/RESET/Reprogram cycle? (I was wondering if my reset circuitry (which uses a 0.1uF cap, and a 10k pullup) might hold the pin low for too long - I notice that the RFDuino USB board uses a 0.01 uF cap (10000pf) and no pullup. I wondered if the longer low time of my circuit may be causing the issue.

Can someone suggest a possible debugging route for me?

Cheers Hugh
« Last Edit: January 12, 2015, 07:32:11 AM by hughanderson »

lsnyman

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Re: Problem with re-programming RFduino on Custom board
« Reply #1 on: January 12, 2015, 07:22:46 PM »
I think the 0.1uF cap is ok as I have used that on some boards, However you should try and disconnect the 10k resistor and see if that solves the issue.