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18 years of Thinkpad Tablet

So 38 days after I ordered it and 31 days after the original ship date I finally have a new Thinkpad Tablet.  Shortly after ordered it I remembered that I have a old Thinkpad Tablet from 1993.  When you look at some of the key features of both of them they are quite similar.


First off the size, they are both roughly the same size length and width, thickness is a different story.  Though screen size is nearly identical.  Unfortunately the 1993 version dosn’t power up any more as I do not have the OS cards for it, at some point in the past I had gotten linux running on it but have no idea where those flash cards went.  Also the batteries are completely shot.

Thinkpad Tablet Docks

Both tablets also have available docking stations with keyboards.  The 1993 version would be a bit tougher to carry around every day.  But even the 2011 version is enormous by today’s standards when but into the dock.  Just for comparison the new Thinkpad Tablet in it’s keyboard ‘Folio’ as Lenovo calls it is bigger then my Lenovo s205 netbook which is pretty insane.  My biggest complaint about the new keyboard folio is that it connects to the only full sized USB port and does not have another on the folio.  I was intending to use the tablet to write this post, but realised to upload the photos I would have to remove it from the folio, then put it back in to finish typing.


The next thing that IBM/Lenovo thought was important in both tablets was printing.  The 1993 version comes with a thermal printer in the dock, in 2011 Lenovo opted for a program called ‘PrinterShare’ being loaded. I don’t own a printer, and even at work I pretty much only use them for printing boarding passes so I really don’t have a use for either of these.


The the new tablet already feels more useful then the Blackberry Playbook which I’m currently using. I will still continue to use the Playbook, mainly for the Blackberry Bridge feature which is great, but the Thinkpad may become my tablet for ‘everything else’ already got some critical applications working that do not on the playbook such as the admin interface to Cisco Communications Manager which is a big one. I’m hoping to get a physical ethernet connection working via the USB host interface but that will be tougher.


Yikes! Invalid device signature.

Published on September 4, 2011, by in Hardware.

So, I got my PCBs in yesterday, imediatly grabbed the solder paste put a bunch of components down, reflowed them and everything looked good.  The power supply was actully very stable, even the components that didn’t have leads looked to be good.  I did know of some errors on the board such as not running VCC, GND, and RST to the ISP header.  Tying AREF to VCC rather then decoupling it. Fixed thoes issues, in the case of AREF I just cut the trace and moved on, no decoupling added. Oh an the biggest oversight on the board design was I left off the power connector.

Many attempts at fixing a non-existent hardware problem.

Many attempts at fixing a non-existent hardware problem.

Imediatly after getting everything fixed, and hooking it up to my ISP programmer I started getting the message that was going to haunt me for the next 24hrs or so.

avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.

I tried everything, followed every trace, added decoupling caps everywhere!  Finally I decided I must have fried the chip when reflowing it and built up another board.  Same results (this one the power supply wasn’t nearly as clean though, need to fix that).

MOSI - Blue, MISO - Yellow , The slave would answer but would fail to read the signature correctly.

What was really bugging me is that I was seeing traffic on both MOSI and MISO which ment both devices were talking to eachother at some point.  I decided it must be something with the board design, went back to the computer and checked everything.  Ran across a couple of posts that mentioned SPI clock speed being an issue, as these are new devices they are set to run off the internal oscillator which is 8mhz, with the divide by 8 fuse set resulting in a 1mhz clock.  Come to find out the default SPI rate in avrdude is  roughly 1mhz which will work for devices running at 4mhz or higher.  Setting the SPI clock down caused avrdude to imediatly recognize the chip as valid on both boards I built.  Tomorrow will be filled with trying to get a bootloader on them, and seeing what if any data I can get in and out of the sensors on the chip.

© Ryan M Sutton, 2015