TinyOS-2.x on Zigbit – Baud rate mismatch

We tried to use TinyOS on Meshnetics Meshbean modules based on Zigbit module containing both microcontroller and radio transceiver. Fortunately a port was made available as a contributed code. I got many student group to start using TinyOS on Meshbean modules. However no one could get the UART communication through USB port working and all the projects which needed this got stalled. I took up this task as I got little free now to figure out what may be happening. It looked like a Baud Mismatch problem since we were received some characters but no baud rate setting was making it come right.

I think I have now understood the problem and however need to try it out tomorrow to make sure that my guess is correct. I am writing it up now and would verify later.

TinyOS port by Distributed Computing Group, ETH used JTAG interface to download firmware into the Meshbean module. This had the capability of programming fues bit as well. What we have been doing is to use Serial Bootloader to program the modules. This does not have the capability of programming the fuse bits. My guess it that due to this the Baud Rates do not match to the right value since clock related fuse does not get set appropriately. I also noticed the default settings of fuse bits are different in Meshnetics software as compared to TinyOS :

Meshnetics : 0xFF, 0x9D, 0x62.

TinyOS : 0xFF, 0x99, 9xE2

So Meshnetics default settings may not work specially since CKDIV8 is the most significant bit of low fuse byte (0x62 vs 0xE2) and can have impact on the clock rate.

I plan to use Dragon to do JTAG programming of Meshbean modules and verify my guess! If it works, we can work on doing Time Synchronization development for seismic measurements.

[Added later : My hunch was correct. Dr Philipp Sommer, who is managing TinyOS port on meshbean also confirmed same. I adjusted some parameters based on his suggestion and it nearly works now. Would update more details in a separate blog.]

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Prabhat Ranjan

Author: Prabhat Ranjan

Prof. Prabhat Ranjan is Vice Chancellor, D Y Patil International University, Akurdi, Pune. He was heading India's Technology Think Tank, TIFAC(tifac.org.in) as its Executive Director since April 2013 to April 2018. Earlier he was Professor at Dhirubhai Ambani Institute for Information and Communication Technology, Gandhinagar (DA-IICT) since 2002. He was educated in Netarhat School(near Ranchi), IIT Kharagpur and Delhi University. He received his Ph D from University of California, Berkeley where he carried our research on “Nuclear Fusion” at Lawrence Berkeley Laboratory during 1983-86. He immediately returned to India after this and carried out research in Nuclear Fusion area at Saha Institute of Nuclear Physics, Calcutta and Institute for Plasma Research(IPR), Gandhinagar. He played a major role in India’s Nuclear Fusion program and was Project Leader of the largest operational Indian Fusion Reactor, ADITYA, at Institute for Plasma Research from 1996-2002. His current interests include applications of Wireless Sensor Network to Wildlife, Planetary Exploration (Chandrayaan mission), Nuclear Fusion, Healthcare, Agriculture etc. He has received National Science Talent Search Award, IBM Faculty Innovation Grant and HP Innovate 2009 award, NPEDP-Mphasis Universal Design Award 2012, Bihar Gaurav Samman 2012 etc.

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Shelly Goodhart
12 years ago

Thanks for this interesting information.