MSP-EXP430G2: UART through Launchpad COM Port emulator not working through USB hub

Hi Andrew,

I don't have an immediate answer for you but I'm working with our tools team responsible for the ez430 on the MSP-EXP430G2. I'll keep you updated on the status of this.

In the meantime, is it possible for you to probe the UART lines with a logic analyzer and verify that the correct data is being sent on those lines? Also, it would be beneficial to ensure the USB hub is providing sufficient power to the LaunchPad especially if many devices are connected.

Best regards,
Caleb Overbay

G'day Caleb,

To minimise the things that could be causing it, I've simply bridged the connection (between the TXD & RXD pins) back to itself creating a loop-back circuit (if that's the correct name for it?). Essentially no signal ever makes it over the "Emulation/MSP-EXP430G2" line. 

The hub is being powered by one of my high power USB 2.0 outputs from my motherboard, but additionally the hub has an external power supply which is 2A. 

I have probed the TXD pin on the MSP-EXP430G2 both with and without the USB hub, both times it correctly pulls the pin high. Only difference is when I send data through a terminal I can see it transmitted without the hub. When I try transmit data when connected to the hub nothing happens, the pin stays high.

EDIT: I also just tried another random USB hub from the shops, same result. Both identify as "Generic USB hub" in device manager. The operating system is Win7 x64

Regards,

Andrew

Hi Andrew,

Thanks for the update. When you connect TX to RX and try to send data while connected to the hub, you mentioned the TXD pin stays high. Does this mean you are receiving 0xFF on the MSP430 when TX and RX are connected regardless of the value you are sending?

Best regards,
Caleb Overbay

Apologies, I didn't make that clear. There are no level changes, not even a start bit on the TXD pin. The pin is pulled high as soon as the board is connected, but never changes when connected through the hub, even while transmitting data from a terminal running on the computer. 

Regards,

Andrew.

Hi Andrew,

Thanks for the clarification. After speaking with our tools team, I have a few more questions for you.

Is the launchpad the only thing connected to the hub or are there other devices connected as well?
What baudrate are you using?

Best regards,
Caleb Overbay

No worries. The Baud rate is 9600, and nothing else is connected to the hub.

Regards,

Andrew

Hi Andrew,

We're having trouble recreating the issue you're experiencing. When the MSP-EXP430G2 was first plugged into the USB hub, it was unresponsive via the UART connection to my PC. Then, simply unplugging then plugging the device in and starting a new TeraTerm session seemed to do the trick. Is the LaunchPad still enumerating correctly on your PC as seen in the image below?

Best regards, 

Caleb Overbay

Hi Caleb,

Attached is a photo from device manager. I downloaded TeraTerm and got the same issue. Tried unplugging and restarting and still nothing.

Interestingly, I found a v1.5 board I was using for another project and tried it out. Nothing! Couldn't get it to loop back connected directly to the computer.

Regards,

Andrew

Hi Andrew,

I apologize for the delay. We're trying to get our hands on a rev 1.4 G2 Launchpad to test this. So far we've been using rev 1.5. However, it looks like you have your jumpers connected incorrectly on the rev 1.5 board for a loopback test. The TX and RX pins of the debugger and target side are mixed. This means that the pins above the dashed line on the board to not exclusively belong to the debugger. One of the pins be longs to the target side. The pins should be connected as seen below to perform a loopback test:

Can you try this out and let me know the results?

Best regards, 
Caleb Overbay

Ah, thanks for pointing that out. Unfortunately I'm away for the next week, but I'll try it as soon as I get home. Maybe the v1.5 was working the whole time, through the hub or not. We'll see!

Regards,

Andrew

G'day Caleb,

I tried out the v1.5 with the correct (doh!) loopback wiring. It worked connected directly, but again, no joy when through the USB hub.

I had high hopes for that test.

Regards,
Andrew

Hi Andrew,

We've been trying to recreate this issue on our end but have been unsuccessful. This may be something specific to the USB hub you are using. Have you tried this with other USB hubs?

Best regards,
Caleb Overbay