updated on 25-08-2012
The display for the power supply status
With the concept of: "Nothing is left unused", the display is another part from the Parking Sensor. After recycling the main board to obtain a Quad Sonar, also the display, with 7 segment numbers and LEDs bars, can be useful for our purposes.
The numbers show a status code, from 0x00 to 0xFF, while the LEDs bars display the levels of the two batteries. The bars are also composed by different colors LEDs to better display the normal, warning and alarm status.
Once more, the modification starts with decoding the circuit to obtain a schematic diagram. In this case it was simpler. In the right part of the schematic there are the remaining components, after removing the original MCU. On the left part you can see the added PIC18F2620 and how its I/O are connected to the board.
The circuit in an intermediary stage of modification.
A flat cable is used to connect the original MCU wiring to the PIC18F2620 added board.
As often happens with MCUs, there are more connectors than components on the board.
Using the internal oscillator for the PIC, we only need a filtering capacitor and a pull-up resistor.
The PIC has been removed to show the components below.
The display controller installed.
The definitive version of the display.