COM Port Question

[TTU_Robotics]

I am trying to use two different COM ports on my Roboard RB-110: COM4 and COM6.

I installed Ubuntu using the tutorials listed on the website to completion. I began testing various aspects of the board. I have working GPIO and PWM. Tested using the example programs. I then tried to test COM4 using a short program similar to some sample code I found here. I also tried using the rbspi.exe example program to test SPI.

I am seeing only ~2.5 Volts. on the output for SPI.

With 5 Volts on Vxx, I am always seeing ~3.4 Volts on the TX pin of COM4.

I was wondering if there is anything I need to do to get these ports working.

I followed the tutorial on activating COM3 and COM4 and updated the BIOS to reflect that. They all show up when using "dmesg | grep tty", but they just aren't doing anything.

[josh]

I followed the tutorial on activating COM3 and COM4 and updated the BIOS to reflect that. They all show up when using "dmesg | grep tty", but they just aren't doing anything.

Hi,
The command "dmesg | grep tty" just show all com ports of the roboard.
ttyS0 is COM1, ttyS1 is COM2, ...

[TTU_Robotics]

I was having no problems seeing them when using the command "dmesg | grep tty"

They show up when I use that command. rbspi.exe doesn't operate as expected. COM4 sample code posted by veltrop with slight modifications doesn't work either.

[roboard]

They show up when I use that command. rbspi.exe doesn't operate as expected. COM4 sample code posted by veltrop with slight modifications doesn't work either.

RB-110 has no native SPI pins brought out, and so rbspi.exe shouldn't work on RB-110. To use SPI interface on RB-110, you may use the FTDI2232H general serial port (COM6); please refer to the RB-110 H/W introduction slides (download from http://www.roboard.com/download_ml.htm) for more information.

RB-110's COM4 is a full-duplex TTL COM port, different from RB-100's half-duplex COM4, and therefore you cannot directly run Veltrop's code (which is for RB-100's COM4) on RB-110. To run Veltrop's code on RB-110, please short the TX & RX lines of RB-110's COM4 first.

[josh]

rbspi.exe doesn't operate as expected.

RB-110 have no SPI devices. The rbspi.exe is unable to work.

[TTU_Robotics]

Most excellent. I was totally overlooking such obvious facts. I've got the FTDI stuff and I'll have to work on that, but you guys have enlightened me. I was starting to worry that the board was bad, and I have deadlines to meet.

Thanks. I will do the new versions of testing of COM4 as half-duplex. I believe that will resolve my problems, and I can move onto bigger and better things. Does anyone have a link for some full-duplex examples? I'll begin scouring the internet on my own, but if someone has a reference link saved, that'd be great.

[TTU_Robotics]

Well, I tied the Tx/Rx lines together, and I was still seeing ~3.4 Volts. Even with 0 Volts on Vxx, there is ~3.4 Volts on both lines. Writing to ttyS3 isn't affecting this voltage.

I'm really confused as to why this is occurring. Does this sound familiar to anyone?

[roboard]

First, be sure thaht COM4 is set up.
Please refer to the file Set up COM3 & COM4 in Ubuntu from the RoBoard web
http://www.roboard.com/Files/RB-100/Ins ... oBoard.zip.

Second, there are the System Power and the Servo Power in RB-110.
Please check that if or not power on the Servo Power.
If the Servo Power is disconnected the electricity, the COM4's Vxx is 0V.
Moreover, COM4's TX/RX are 3.4V normally.
refer to http://www.roboard.com/Files/RB-110/RB1 ... W_v20e.pdf

Finally, when testing COM4, check that TX really send data to RX.