Custom T4.1 bringup -> 4 Blinks = ARM JTAG & SWD Not Responding (Needs Crystal)
I'm bringing up my third custom T4.1 design today and this time around it wasn't working (the previous two worked great). The blink code from the MKL02 indicated that the 24Mhz crystal was not oscillating and that was confirmed by testing with an oscilloscope. No oscillation, but just a very weak DC noise on the XTAL lines. I looked at the documents from the PCBA manufacturer and they had used 0.22uF caps instead of the 10uF caps required. Changing the caps to the correct value solved the issue. Big thanks for making this so smooth Paul! This troubleshooting list is Gold!
I have one question regarding the MKL02 status LED. When all was good, it was blinking at a steady pace on/off. I could not find this documented and I sat there counting blinks until I got past the number of blinks in the troubleshooting list ;-)
I'm bringing up my third custom T4.1 design today and this time around it wasn't working (the previous two worked great). The blink code from the MKL02 indicated that the 24Mhz crystal was not oscillating and that was confirmed by testing with an oscilloscope. No oscillation, but just a very weak DC noise on the XTAL lines. I looked at the documents from the PCBA manufacturer and they had used 0.22uF caps instead of the 10uF caps required. Changing the caps to the correct value solved the issue. Big thanks for making this so smooth Paul! This troubleshooting list is Gold!
I have one question regarding the MKL02 status LED. When all was good, it was blinking at a steady pace on/off. I could not find this documented and I sat there counting blinks until I got past the number of blinks in the troubleshooting list ;-)