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→Battery Backup
== Battery Backup ==
== Battery Backup ==
The GPS has a built in real time clock, which can keep track of time even when it power is lost and it doesn't have a fix yet. It can also help reduce fix times, if you expect to have a flakey power connection (say you're using solar or similar). To use the RTC, we need to attach a battery. There is a spot on the back for a CR1220 sized battery holder. We provide the holder but the battery is not included. You can use any 12mm coin cell - these are popular and we also carry them in the Adafruit shop.
The GPS has a built in real time clock, which can keep track of time even when it power is lost and it doesn't have a fix yet. It can also help reduce fix times, if you expect to have a flakey power connection (say you're using solar or similar). To use the RTC, we need to attach a battery. There is a spot on the back for a CR1220 sized battery holder. We provide the holder but the battery is not included. You can use any 12mm coin cell - these are popular and we also carry them in the Adafruit shop.
[[Fichier:GpsUltimatePile1.jpg]]
Before inserting a battery into the battery holder, first cut the trace between the two solder pads on the back, labeled RTC (this disconnects the VIN pin from the battery input) Use a multimeter with continuity checking to verify the two pads are no longer tied together.
[[Fichier:GpsUltimatePile2.jpg]]
== Advanced Wiring ==
Thus far we've only used the '''VIN GND TX''' and '''RX''' pins of the GPS - but there are many other pins. What do these do and will you ever need them? Chances are, for 90% of GPS projects, the other pins are not required. But we do make them available in case you have a specific need.
'''FIX''' is an output pin - it is the same pin as the one that drives the red LED. When there is no fix, the FIX pin is going to pulse up and down once every second. When there is a fix, the pin is low (0V) for most of the time, once every 15 seconds it will pulse high for 200 milliseconds
'''VBAT''' is an input pin - it is connected to the GPS real time clock battery backup. We suggest using the battery spot on the back but if you have a project with a coin cell or other kind of battery that you want to use (and its under 3.3V) you can connect it to the VBAT pin. If you do this, be sure to cut the trace on the back between the RTC solder pads
'''EN''' is the Enable pin, it is pulled high with a 10K resistor. When this pin is pulled to ground, it will turn off the GPS module. This can be handy for very low power projects where you want to easily turn the module off for long periods. You will lose your fix if you disable the GPS so keep that in mind.
'''3.3V''' is the output from the onboard 3.3V regulator. If you have a need for a clean 3.3V output, you can use this! It can provide at least 100mA output.
== Source ==
== Source ==