Vermes
Advanced Member level 4
It is a car GPS Logger – useful tool when you want to record traveled route. The main element of the system is Atmega328P in housing TQFP32. Atmega communicates with receiver (GPS SC-GPS-1 from JENTRO) in two directions through hardware UART with speed of 115200. In order to receive frames from the receiver correctly (faultlessly), the device uses quartz 7.372800MHz. The whole is powered by mini-USB port from a car charger or another source which gives 5V at the output and at least 200mA, ended with mini-USB plug. There is a stabilizer LD33 on the board, which powers the processor and SD card. The GPS receiver requires 5V to the correct operation. Polymer fuse was also added.
The principle of operation:
When powered, the processor flashes the LEDs alternately for 5 seconds. This is the time needed to properly run the GPS receiver. Then the command is sent which switches the receiver into the GPRMC frame sending mode (every second). By default, the GPS sends frames GPGGA and GPRMC. You can also set different frames. More details can be found on the documentation of the system Sony CDX2951.
When the work is started, the system waits until the GPS synchronizes with the satellites and starts sending the correct GPRMC frame. Green diode is lit and the red diode changes its state every second.
If the frame is correct, the system goes to the proper work, where the full frames are stored on the SD card. Every fifth received frame is stored. In addition, in order to protect the card, the system checks if the receiver has moved since the previous record. So if the car will be stopped for longer time, there will be only one record from that place. Green diode indicates the correct receive of the GPRMC frame while the red diode indicates the moment of storing.
Pictures:
And recorded routes (exported to Google Earth):
Operation during the driving:
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