Add console serial port on external 3.5 mm jack
Posted: 10 Sep 2012, 09:16
There are connections on the B2/B3 boards for 3.3V serial console access. There are also mount points for 5V level conversion and DSUB connector. I would guess these are for development use, and for cost reasons not mounted on production units.
Console access is absolutely crucial for troubleshooting various boot problems. I recently had an issue with a faulty file system (due to some unclean shutdown probably) which was solved by running fsck from console. There was (obviously) no network, and the only indication of the nature of the problem was the blue led which kept on flashing.
I had to solder the serial lines myself, from information and cad images found here and there on this forum. I managed to make a mistake the first time, and had to re-solder to make it work. Which made me wonder; as this is such an invaluable feature, why isn't this already provided?
To save cost and space from the 5V-DSUB approach, my suggestion is to update the hardware design, and add an external 3.5 mm phono jack with just the 3.3 V RX, TX and GND lines. The console port can then be accessed using the commercially available FTDI USB conversion cable TTL-232R-3V3-AJ. (Google it -- That's USB, cable, 3.3 V conversion and phono plug all in one.)
This way you can enable console access at a minimum cost without making it necessary to open the box or soldering on the board. Just add the 3.5 mm hole on the back and label it "console".
Otherwise it's a great product etc etc. Keep it up!
Console access is absolutely crucial for troubleshooting various boot problems. I recently had an issue with a faulty file system (due to some unclean shutdown probably) which was solved by running fsck from console. There was (obviously) no network, and the only indication of the nature of the problem was the blue led which kept on flashing.
I had to solder the serial lines myself, from information and cad images found here and there on this forum. I managed to make a mistake the first time, and had to re-solder to make it work. Which made me wonder; as this is such an invaluable feature, why isn't this already provided?
To save cost and space from the 5V-DSUB approach, my suggestion is to update the hardware design, and add an external 3.5 mm phono jack with just the 3.3 V RX, TX and GND lines. The console port can then be accessed using the commercially available FTDI USB conversion cable TTL-232R-3V3-AJ. (Google it -- That's USB, cable, 3.3 V conversion and phono plug all in one.)
This way you can enable console access at a minimum cost without making it necessary to open the box or soldering on the board. Just add the 3.5 mm hole on the back and label it "console".
Otherwise it's a great product etc etc. Keep it up!