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What does J-state error mean?

Posted: Sat Jul 11, 2015 1:44 pm
by bryankazan
I'm writing some microcontroller code to interface between the Max3421E Host chip and a Silicon Labs CP2103 usb slave / target chip. I have my host driver to the point where it's initializing the CP2103, setting baud rate, querying the status of the serial port, seeing bytes fill up the rcv buffer from a serial source, etc.

At that point I then try to command the Max3421e to issue a BULK_IN command to the slave in order to start transferring the actual serial bytes across USB. This is where I'm getting the code 0x0D back from the Max chip, meaning a J-state error, and I'm stuck on what's causing this.

I've googled this and found a bit of information about J and K states on USB, but very little on what can cause such an error.

Any help would be greatly appreciated!

Thank you,
Bryan

Re: What does J-state error mean?

Posted: Sun Jul 12, 2015 8:24 am
by bryankazan
Since I posted this, I've learned a bit more, and I'm assuming (could still be wrong) that this error is resulting from the fact that the slave device, when seeing the BULK_IN token, still doesn't think it is allowed to respond to anything beyond CONTROL traffic.

The last thing that I thought I needed to do was to issue it a SET_CONFIG command, which I'm now doing, but still getting the 0x0D error.