Solder jumpers

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ZeroPhone boards have some solder jumpers that you might want to cut/connect in order to enable and disable certain ZeroPhone features. By default, those solder jumpers are already set into reasonable states, however, if you install some addons or want to modify the boards in a certain way, you might want to change the state of some particular jumper.

Delta-B and Delta revision

Back board

Jumper name (on PCB) Function
JP1 GSM power jumper - can be used for a DIY GSM killswitch, until a proper software/hardware-driven killswitch is added to ZeroPhone boards. By default, is connected, so in order to disconnect anything, a trace needs to be cut.
JP11 IR RX jumper. Connects RPi GPIO17 to the top 5-pin header IR RX pin, open (unconnected) by default. Regardless of whether the jumper is connected or not, GPIO17 is also connected to the bottom header.
JP12 IR TX jumper. Connects RPi GPIO4 to the top 5-pin header IR TX pin, open (unconnected) by default.
WE 24c32 EEPROM write enable pin, connect pads with solder to enable writes into the EEPROM. By default is disconnected.

Front board

Jumper name (on PCB) Function
JP1, JP2 Audio buffer board connection override. Connected by default, if you want to install an audio buffer board (or some other board that goes in the audio buffer board socket), you'll want to cut both of these jumpers first.
JP3 A two-position (three-pad) jumper where the center pad leads to the RST pin on the ATMega 6-pin header. You can replace the RST on the pin header with the free ATMega GPIO (PD5) if you cut the existing connection and connect the center pad with the opposite pad.
JP4 Short to connect the RPi GPIO used for SPI display (GPIO5) to the free keypad GPIO (1-pin pad next to the 4-pin keypad I2C header). If you have a display that doesn't use the RST pin, you can use a modded keypad which could make use of this GPIO instead.
JP5, JP6 TPA2003 override, left for development purposes and for those attempting self-assembly that can't source a TPA2003. Jumper these two jumpers only (and only if) if you don't have a TPA2003 speaker amplifier installed and you don't have the ability to install one.