problem programming a bare moteino (no radio) [SOLVED]

[damonb]

hi all.
I have a couple of new bare Moteinos (no radio, no flash chip). I can't get them to respond to the FTDI interface to upload a sketch.

When I plug them in to my FTDI adapter, I see the onboard LED flashing, but can't get any response.

When I try to upload a sketch (using the Arduino IDE - tried 1.6.4 and also latest version 1.8.7), there is no activity from the FTDI TX/RX LEDs, and eventually the upload times out.

I can't get anything from the USB serial port using a PuTTY either.

The FTDI is a USB-BUB II from Modern Device. I know it is working, because I can reliably program an older Moteino R4 I have on hand (one that has a RFM69 and flash chip).

The LED blink pattern is interesting. It seems to boot, then blink about 50 or 60 times at around twice per second, then stop for a few seconds, then blink a few more times, then goes out. It then blinks sequences of 4 to 12 times at random, with a gap between. I'm not sure if it's some kind of code.

@Felix, do you load the same pre-shipping test sketch when there is no radio fitted? What is the expected behavior? Does it involve blinking the LED? Or could this be some kind of bootloader behavior that I've never heard about? I am perplexed.

[Felix]

All moteinos will get a test sketch to verify the upload and any optional peripherals. The moteino with no radio/flash should blink the LED quickly when you apply power to it (GND, VIN). This test is done with a LPL FTDI-Adapter, that gives 5v power and 3.3v on serial lines.

Either someone reported some problem with the BUBII or it was me testing on my own sometime ago and I found some upload issue, I can't remember for sure and what it was, so I won't claim that here, but it would be good if you had another device to cross test. Not sure what else to suggest, if you feel you want to send this back I can re-check it for you.

[damonb]

I tried another USB/serial adapter - based on a CH340 chip. This one worked with the Moteino R6, so all good now... Thanks Felix.

I don't understand why the USB-BUB II works reliably with the Moteino R4, but not at all with the R6. It always works with my JeeNodes too.

[Felix]

There are some changes to R6 that include an added cap on the DTR line. If the BUBII doesn't use DTR this may be the reason.

[andymcl]

Oh my, I'm glad I found this as I've been tearing my hair out (and not much to start with) with exactly the same problem - R4 works, R6 doesn't. I was derailed because I have 3 FTDI adapters and they are BUB and BUB2 adapters! So I guess I'll get some new adapters