This page will describe the standard connections to your 912D60 board.

Critical Connections

There are three critical connections to the 912D60 board, and three optional connections.

The PWR Connector

Your 912D60 board is designed to run on a 5 volt power source. The board should operate within norms at voltages between about 4.9 volts and 5.8 volts. However, a regulated 5 volt power supply is the best method of providing power. The connector itself has two GND pins and 1 +5v pin. The GND pins are interconnected on the board.

There is no power switch on the board.

The PWR-VFP Programming Power Connector

Your 912D60 board requires a REGULATED +12 volt power supply for programming the Flash memory. This +12 volt supply is only required if you are planning to program or erase the onboard Flash EEPROM. It is not required for normal operation of the board.

The 912D60 Flash EEPROM is sensitive to specific voltage levels. Therefore, you should insure that you only use a REGULATED 12 volt power supply. A non-regulated supply will damage the part as they typically have voltages in excess of 12 volts. You should check your power supply with a voltage meter to insure that the voltage is between 11.8 volts and 12.2 volts. Exceeding this range will damage the chip. This connector is labeled PWR-VFP on the board.

Note, if you are using a 912D60A or other 'A' variant, you will not need PWR-VFP]

The BDM12 connector

Your 912D60 board has a connector for interfacing with the Background Debug Module on the 68HC912. This connector uses the Motorola standard 2x3 connector. My BDM12 pod is the usual thing to connect here. You should make a note of which is pin 1. It is marked on the board. Be sure the orientation is correct when you connect a BDM pod to this port.

The Optional Connections

The 2x5 PORT Connectors

There are a total of nine 2x5 headers that connect to most of the ports on the CPU. Of the nine connectors, seven are laid out the same. Two of the ports, specifically the A/D ports, are different, and will be described below. Each of the 2x5 headers has a VSS and VDD connections. These are always pins 1 and 2 respectively. On the schematic, these ports all follow the same format as PORTA, shown below.

On the PCB, you will find that the ports all follow the same layout as PORTA as well. For example, if you look at the PORTA connector, it has the following layout

Of things to note, pins 1 and 10 are marked on the silkscreen. You need to check this marking on the board. To get the board layout to route correctly using 2 layers, some of the ports have been rotated 180 degrees from the others. Be sure you understand which is pin 1 before you make a connection.

The A/D converter was handled slightly differently. Here are the layouts on the schematic.

As you can see, PORTADX and PORTADY each have 4 pins each from AD0 and AD1. This was done to make the routing work out. You will need to insure you have the correct orientation if you plan to use these connectors.

The 1x3 IOC connectors

Each pin of the Input/Output Capture system is brought out to PORTT. In addition, you can find these pins duplicated on the eight IOC connectors. Each IOC connector has a VDD, VSS, and a IOCx [0-7] channel pin. You can use these to connect devices directly to the timer channels, such as servo motors, quadrature encoders, etc.

Pin 1 is always VSS, pin 2 (the center pin) is VDD-IOC, and pin 3 is connected to the appropriate IOC channel on PORTT.

The PWR-IOC Connector

The PWR-IOC connector allows you to provide a seperate supply voltage for the IOCx pins. The connector is a 2 pin, and doesn't usually need to be installed. If you connect a seperate power supply, you will need to cut jumper JP5 on the backside of the board to disconnect VDD on the IOCx pins from VDD for the rest of the board. Note thate PWR-IOC shares VSS with the other power connectors.

Main Board Interconnect