26 Jul
2013
26 Jul
'13
11:05 p.m.
Excerpts from Tom Schouten's message of 2013-07-26 22:55:32 +0200:
Hi folks,
Seems not all phones use 3V signaling if the PHONE-side VCC pin is tied
to 3V.
This one insists on 1.8V : BLU SAMBA JR PLUS
how does the phone behave?
Is this trick of tying VCC to 3V standard behavior?
no, it is not standard. It just works (most of the time).
And it should not damage the SIM nor the phone.
For future version of the board, it might be interesting to tie the VCC
pin to an ADC input, to detect different voltage levels so the firmware
can wait until phone decides to use 3V.
this will be done in the next board
Cheers
Tom