In brief, I assembled a RBBB board, recently purchased. It seems to work fine in the sense that the power light comes on, and pin 13 blinks in this pattern:
On for 0.1s, off for 1.286s, repeat.
I am trying to program it, on a Mac using OS/X with this: "USB FTDI TTL-232 cable - TTL-232R 3.3V" (from Adafruit). According to their site:
Well, maybe.These are perfect for use with a Boarduino, Meggy's, or other Arduino clones, and Fuzeboxen.
The version we have is the 3.3V. The data signals are at 3V and the power line provides 5V. We suggest this for any product that needs FTDI cables.� Because the cable is 5V compliant, you can use it with 3v or 5v logic just fine - no level shifting required!.
If you have a device that is running at 5V logic and requires 5V power, this cable will work fine.
I have done extensive tests to try to work out whether it is user error (me), lack of reset pulse, wrong choice of board, etc. So far I have this (measured on the pins of the Atmega itself, to eliminate the possibility of soldering problems):
RTS is being taken from high to low at the start of the upload. The board responds by taking the reset line from high to low for around 60 us.
About 0.25s after reset is asserted, the Rx pin (D0) receives at 115200 baud the following: 0x30 0x20.
There is no response on the Tx pin (D1).
However measuring the same attempt to upload on a Uno board, I also get 0x30 0x20, but the board responds with 0x14 0x10.
After a little while the Arduino uploader says:
Code: Select all
Binary sketch size: 1018 bytes (of a 32256 byte maximum) avrdude: stk500_recv(): programmer is not responding avrdude: stk500_recv(): programmer is not responding
According to measurements made with an oscilloscope the peak to peak voltage on the Rx pin is 3.84V.
Am I doing something wrong, or would you say the FTDI cable is not putting out enough voltage for the signal to be recognised?
Thanks for any assistance.