I've built a custom board with a MKL04 and MK20DX256. I tried to follow the design rules strictly, including Vbatt and the oscillator.
When I power up, the reset pulse is on the reset line as expected. No problem.
The program button drives reset low, then high.
The oscillator turns on; 16 MHz. There is no noise on the oscillator. The waveform looks just like a Teensy oscillator.
There is some data on USB P/M.
Cycling power at this point restarts this process.
So far, so good. It seems like a lot is correct so far. The MKL04 must be good, oscillator must be good (?), etc.
To program, I select Raw HID (Serial gives same result) from Arduino. The Upload process invariably causes a "Download Error" message when I try to load Blink and the processor resorts back to the reset pulse mode. A couple of times, a program loaded into flash, but it was not a working Blink. I'm guessing a corrupted Blink. I can download Blink to a genuine Teensy, no problem.
I suspect that the USB lines are not optimum, but I expected the USB lines to be pretty robust.
I can re-spin the boards with new USB routing, but I just wanted to toss this out for a sanity check first.
Anybody have any thoughts?
When I power up, the reset pulse is on the reset line as expected. No problem.
The program button drives reset low, then high.
The oscillator turns on; 16 MHz. There is no noise on the oscillator. The waveform looks just like a Teensy oscillator.
There is some data on USB P/M.
Cycling power at this point restarts this process.
So far, so good. It seems like a lot is correct so far. The MKL04 must be good, oscillator must be good (?), etc.
To program, I select Raw HID (Serial gives same result) from Arduino. The Upload process invariably causes a "Download Error" message when I try to load Blink and the processor resorts back to the reset pulse mode. A couple of times, a program loaded into flash, but it was not a working Blink. I'm guessing a corrupted Blink. I can download Blink to a genuine Teensy, no problem.
I suspect that the USB lines are not optimum, but I expected the USB lines to be pretty robust.
I can re-spin the boards with new USB routing, but I just wanted to toss this out for a sanity check first.
Anybody have any thoughts?