Serial data out of the programming port

[Doug Leppard]

We are using a data logger see url:
http://www.sparkfun.com/commerce/pro...roducts_id=752

We are using the programming port, not the TTL level port 2, we tried that but could not get it to work well. We use a TTL to RS232 level converter to be able to use that port.

The logger works on the programming port but at times the competition drivers think that they loose control when it is plugged in.

Looking at the specs of the logger once a buffer is filled up it switches to another buffer to write out the data. It may be sending out a wait for buffer signal, I am not sure.

Question, if the logger tells the port to wait for data to be received will that cause the RC and thus the OI not to process the data and cause the loss of control for the operators of the robot?

[Nathan]

I could be wrong, but it's my understanding that the port is always "waiting" for data. I believe an ISR runs every time new data arrives and stores the new data on a ring buffer.

If the RC doesn't process data at a certain rate the "watch dog" timer tells the system to reboot. So if it is freezing watch for an RC reset.


Nathan

[Doug Leppard]

Originally Posted by Nathan

I could be wrong, but it's my understanding that the port is always "waiting" for data. I believe an ISR runs every time new data arrives and stores the new data on a ring buffer.

If the RC doesn't process data at a certain rate the "watch dog" timer tells the system to reboot. So if it is freezing watch for an RC reset.

Nathan

How longs does the reset take and how do you tell if it is reset?

[Nathan]

I don't know how long it takes. I do know in the past when I've downloaded some bad code to the RC (infinate loop for example..) the RC reset itself because the lights cycled off and then came back on. I assumed that was the "watchdog" timer that I've heard about, but it's possible it was just a freak of nature :-)

Do you always make sure the backup battery is charged? We've lost control of our robot (not a competition) in when the backup battery was low.

How do you get the debugging data to your chip, and how fast do you put it there? I integrated a camera through the TTL port and for the longest time had problems because I was printing something out during an interrupt routine.


Nathan

[Doug Leppard]

We tried the TTL port but it didn't work right, so we are using the programming port just like if you had your laptop hooked up.

I only suspect that it causes the loss of control, the drivers said when it was in they had problems but when it was off they had no probelms.

Who knows.

[Kingofl337]

Doug,

I'm not sure if a wait commend via flow control will effect the RC and cause it to stall. I feel that it is very unlikely, and that RC just ignores any type of flow control. But, to be sure if I was in you situation I would build a serial cable with only ground and RX pins connected on the logger end. This would assure that you logger isn't effecting the RC it wouldn't be able to send any data back to the RC.