TinyCircuits

Possibility of updating the bootloader on TinyScreen+ ?

Possibility of updating the bootloader on TinyScreen+ ?
« on: June 04, 2018, 09:36:22 AM »
Hi,

I have two TinyScreen+ for my project, but it looks like both are running a different version of the bootloader.
When I go into the bootloader mode on both, one of them shows a black screen, while the other prints a text like "Bootloader Mode".

Is there an easy way of getting access to the latest bootloader and updating the tinyscreen with it?
It's just difficult to make out if the Tinyscreen is running in Bootloader mode of being turned off when there is nothing on the screen.

Cheers
thesko

Re: Possibility of updating the bootloader on TinyScreen+ ?
« Reply #1 on: June 24, 2018, 08:00:06 AM »
Any infos on this @TinyCurcuits team?

I also realized that my second TinyScreen is unable to read the battery state using the new tutorial.
Is it possible that I have two different hardware revisions?
And if so, is it possible to update also the hardware somehow for the voltage reading?

Please help!
- the sko

Re: Possibility of updating the bootloader on TinyScreen+ ?
« Reply #2 on: July 12, 2018, 07:30:40 AM »
still no answer...  :( I guess there is no way to do this?

Re: Possibility of updating the bootloader on TinyScreen+ ?
« Reply #3 on: July 12, 2018, 11:19:09 AM »
Sorry! Thought I had responded after your post on the 24th. Yes, it sounds like one board is the older revision- if I remember correctly the only release versions are 3 and 4, which will be silk screened on the PCB in very small font near the 32 pin connector. Rev 4 adds the battery voltage divider, as well as the bootloader change to display text. The voltage divider is just that- two 1M ohm resistors in series from the battery to ground, with the center tap connected to an analog pin. This results in pretty minimal current draw while allowing the ADC to still get a reasonable reading.

There shouldn't be a direct problem preventing updating the bootloader from a user program, but there wouldn't be any backup without being able to reflash with an external programmer- an error would probably brick the board, but there should not be an error :). I can look into this shortly if you're interested in trying it.

Re: Possibility of updating the bootloader on TinyScreen+ ?
« Reply #4 on: July 17, 2018, 09:36:20 AM »
Hey Ben!

Glad to get an answer :)
So to make sure I got it right:
Code: [Select]
Bat+
 |
[1M ohm]
 |
 |--> Analog A4
 |
[1M ohm]
 |
GND

If that is the case I could hack it into the board I have here and use the example from here to read it:
https://tinycircuits.com/blogs/learn/tinyscreen-battery-voltage


About the bootloader:
I have a CP2102 USB to TTL converter, but in any case, since the TinyScreen+ does not have any visible headers for a programmer I fear this will be too risky just for getting a bootloader screen :P
Getting the battery readout is all I really needed compared to the previous version.

So if you can verify my ASCII diagram above I'm good :)

EDIT: I just realized that the schematics were attached to this post:
http://forum.tinycircuits.com/index.php?topic=1779.msg3786#msg3786

Cheers and thanks!
Andreas
« Last Edit: July 17, 2018, 09:45:21 AM by thesko »