Pasky’s Log

So, thanks to very helpful Rickta59 on #43oh IRC channel, I got my Launchpad v1.5 serial communication working. The key piece of information I was missing:

This is even drawn on the board, but it just didn’t occur to me that I need to do this simple thing. Most examples seem to use hardware UART, and Energia Serial class also uses hardware UART.

It is still very flaky:

• For the first ten seconds, communication is impossible. Wait for timeout messages to appear in dmesg, then you can start communication.
• When the board is sending data, something must be reading them on the host side. If not, the driver collapses and you need to replug the device.
• The latter might be circumvented by direct USB communication without involving the tty driver.

So, it is rather fragile, but usable! Let’s enjoy our Launchpads for projects where this is not a big issue…

I found out that the situation with MSP430 is not as bad as it seemed. This post is mostly obsolete, but I’m leaving the text up for the benefit of Google index and other desperate people struggling with their Launchpad. :-)

This blogpost serves as a big fat warning to the future ones that might be about to follow in my footsteps:

It’s a sad reality but that’s just how it is, to the best of my knowledge, and after a lot of research and doing unbelievable things to kernel drivers etc. To clarify a bit, basic programming using mspdebug works, but you cannot communicate between host and board using USB serial. This seems to have worked with much older USB chips but not with the ones used by TI in current versions of the board (I got Launchpad with MSP-EXP430G2 ordered in May 2012).

Some fun technical details to help google index and guide others diagnosing this:

[186808.775510] usb 1-1.2: new full-speed USB device number 7 using ehci_hcd
[186808.891778] usb 1-1.2: New USB device found, idVendor=0451, idProduct=f432
[186808.891788] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[186808.891794] usb 1-1.2: Product: Texas Instruments MSP-FET430UIF
[186808.891800] usb 1-1.2: Manufacturer: Texas Instruments
[186808.891804] usb 1-1.2: SerialNumber: CFFF4695F6C11445
[186808.924900] cdc_acm 1-1.2:1.0: This device cannot do calls on its own. It is not a modem.
[186808.924914] cdc_acm 1-1.2:1.0: No union descriptor, testing for castrated device
[186808.925029] cdc_acm 1-1.2:1.0: ttyACM0: USB ACM device
[186808.927595] usbcore: registered new interface driver cdc_acm
[186808.927603] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
[186818.963279] generic-usb 0003:0451:F432.0001: usb_submit_urb(ctrl) failed
[186818.963332] generic-usb 0003:0451:F432.0001: timeout initializing reports
[186818.964177] generic-usb 0003:0451:F432.0001: hiddev0,hidraw0: USB HID v1.01 Device [Texas Instruments Texas Instruments MSP-FET430UIF] on usb-0000
:00:1a.0-1.2/input1
[186818.964262] usbcore: registered new interface driver usbhid
[186818.964269] usbhid: USB HID core driver

This is what my dmesg says the first time the board is plugged in. mspdebug works fine but any attempt of serial communication over /dev/ttyACM0 (talking to TI-provided sample UART code). OBTW if you are actually wondering how to compile and upload stuff on this baby:

msp430-gcc -mmcu=msp430g2553 -Wall -O3 -o uart_01_9600 msp430g2xx3_uscia0_uart_01_9600.c
mspdebug rf2500 prog\ uart_01_9600

For USB interface, TI includes its own crazy USB-enabled microcontroller on board that provides a HID-ish interface (for mspdebug) and an ACM-ish interface (for UART emulation) on a single port (which is nicely confusing). The serial part is supposed to be handled by ti_usb_3410_5052 kernel driver, which grabs a firmware and attempts to reflash the USB microcontroller so that it presents a more sensible serial USB interface (pretty crazy, eh?). However, the rf2500 variant of this chip appears to be too new and simply not supported either by the firmware or the firmware uploader.

Tweaking USB ids in the driver (f430 -> f432) does not help. Getting ti_3410.fw that Debian helpfully does not ship does not help. Manually binding the driver to USB does not help. The furthest I get is that the driver indeed tries to flash the ti_3410.fw firmware to device, but just times out doing that (I think maybe I bricked the serial part of the USB microcontroller by now):

[193053.430662] ti_usb_3410_5052 1-1.2:1.0: TI USB 3410 1 port adapter converter detected
[193054.443490] usb 1-1.2: ti_download_firmware - error downloading firmware, -110
[193054.443528] ti_usb_3410_5052: probe of 1-1.2:1.0 failed with error -5

Oh, and mspdebug rf2400 exit before any serial communication (I have found a tip somewhere) does not help either. An obviously-working UART code for MSP430G2553 would be welcome too, to triple-rule-out a uC-side firmware problem. (The launchpad board is awesome but rx/tx leds are sorely missing. I know, I could grab an oscilloscope… but how many hours have I already wasted by this?)

So, what seemed to be a great Arduino replacement turns to dust for me since the whole point of 80% of my Arduino projects is to talk to a computer… That said, if (after) you make it work, you will get one, or maybe even two Launchpads for free from me.