Port B is an 8-bit bidirectional I/O port with internal pull up resistors. They can therefore be used as both inputs and outputs. For this reason they are used to program the ATMEGA328P-PU pins PB3, PB4 and PB5 as MOSI, MISO and SCK respectively. Port C6/RESET is used as an I/O pin. In our case PC6 was used as a reset input. A low level on this pin for longer than the minimum pulse length will generate a reset even if the clock is not running. We need to use an external 10KΩ pull-up resistor to the reset pin. Port D is an 8-bit bidirectional I/O port with internal pull up resistors, this is the reason pins PD0 and PD1 were used as transmission and reception pins. The port D output buffers have symmetrical drive characteristics with both high sink and source capability, this is the reason why port PD5 was used to power the SIM908 module. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The port D pins are tri-stated when a reset condition becomes active, even if the clock is not running. All ground connections are shorted and connected to GND. To be able to program the microcontroller, a six pin AVR_SPI connector was integrated in the design circuit of the tracker and was connected as shown on the diagram. ATMEGA328P-PU circuit connection diagram AVR SPI 6 pin connection diagram Selection NETLIGHT Circuit This is a net status indicator. It can a transistor to control a LED which will blink slowly or quickly according to different states. The module cannot drive the LED directly on its own hence the need of the transistor.
Port B is an 8-bit bidirectional I/O port with internal pull up resistors. They can therefore be used as both inputs and outputs. For this reason they are used to program the ATMEGA328P-PU pins PB3, PB4 and PB5 as MOSI, MISO and SCK respectively. Port C6/RESET is used as an I/O pin. In our case PC6 was used as a reset input. A low level on this pin for longer than the minimum pulse length will generate a reset even if the clock is not running. We need to use an external 10KΩ pull-up resistor to the reset pin. Port D is an 8-bit bidirectional I/O port with internal pull up resistors, this is the reason pins PD0 and PD1 were used as transmission and reception pins. The port D output buffers have symmetrical drive characteristics with both high sink and source capability, this is the reason why port PD5 was used to power the SIM908 module. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The port D pins are tri-stated when a reset condition becomes active, even if the clock is not running. All ground connections are shorted and connected to GND. To be able to program the microcontroller, a six pin AVR_SPI connector was integrated in the design circuit of the tracker and was connected as shown on the diagram. ATMEGA328P-PU circuit connection diagram AVR SPI 6 pin connection diagram Selection NETLIGHT Circuit This is a net status indicator. It can a transistor to control a LED which will blink slowly or quickly according to different states. The module cannot drive the LED directly on its own hence the need of the transistor.
VEHICLE%20TRACKING%20USING%20GPS.docx