the protruding through hole pins of the header for the jumper
might get shorted when the board lies on a conductive surface,
leading to unwanted flash erase (JP2) or false TST signal (JP1)
Change-Id: I7fc6176d8c63ab8274b641e7bcd990093af3c4ca
R22 is use to pull the FLAGB output of the FPF2109 high since this
is an open-drain output.
but we actually don't read FLAGB do get the error conditions, thus
thus pull-up resistor is not required.
this change has been tested with a real simtrace device.
trace and card emulation worked with a Nokia 3310.
Change-Id: I3dd82864708f1ecb30ddbaa4c60aa600325455e2
R24 is pulling the voltage regulator output for VCC_SIM down.
it has probably been added at the same time as R15.
since we don't read VCC_SIM it is not important to have it in a
defined state.
also the card, phone, or simtrace will provide power to the card
when required (else the card load is high enough to immediately
pull it down).
this change has been tested with a real simtrace device.
trace and card emulation worked with a Nokia 3310.
Change-Id: Iaae0959b62bc9348279bc5d840addbeb28fdf98f
R15 is pulling VCC_SIM down.
it has probably been added because a load resistor is present in
the FPF2109 datasheet example application, or to not have VCC_SIM
in tri-state.
since we don't read VCC_SIM it is not important to have it in a
defined state.
also the card, phone, or simtrace will provide power to the card
when required (else the card load is high enough to immediately
pull it down).
current flowing from the other card pins back to VCC should not
happen, and if it happens this high value resistor will not have
any effect.
this change has been tested with a real device.
trace and card emulation worked with a Nokia 3310.
Change-Id: I002b1fcf1039c8910d902e476a47183172d70761
- VCC is up
- GND is down
- group the parts by functionality and use net name
- separate decoupling capacitors
- arrange groups from left input to right output
Change-Id: I2d894dd10b8b619ccbce1ae8b7e25316963157c8
If the LDO is switched off, then even if we try to forward power from
the phone to the SIM, the current will sink inside the LDO (no reverse
current protection).
