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Wiring your MC68HC912B32

A first looking at the MC68HC912B32 looks dauting. But if you just take it one step at a time, things will slowly come together.

MC68HC912B32 Microcontroller
Diagram
Image courtesy of ECE Shop

Pin Description

HC912 Chip Pin #'s - In order as they appear on the ECE module	Description
Pin 35	(LSTRB)'/PE3 - Low-Byte Strobe/Port E
Pin 37	(IRQ)'/PE1 - Maskable Interrupt Request pin/High voltage supply to EEPROM used for test purposes only in Special modes/Port E
Pin 39	ADDR8/DATA8/PA0 - External Address/Data Bus/Port A
Pin 41	ADDR10/DATA10/PA2 - External Address/Data Bus/Port A
Pin 43	ADDR12/DATA12/PA4 - External Address/Data Bus
Pin 45	ADDR14/DATA14/PA6 - External Address/Data Bus/Port A
Pin 47	VDD - Internal power and ground
Pin 49	VRH - Reference voltages for the analog-to-digial converter
Pin 51	PAD0/AN0 - Port AD/Analog inputs
Pin 53	PAD2/AN2 - Port AD/Analog inputs
Pin 55	PAD4/AN4 - Port AD/Analog inputs
Pin 57	PAD6/AN6 - Port AD/Analog inputs
Pin 59	VDDA - Operating voltage and ground for the analog-to-digital converter, allows the suppply voltage to the A/D to be bypassed independently
Pin 61	PS0 - Port Signals
Pin 63	PS2 - Port Signals
Pin 65	PS4 - Port Signals
Pin 67	PS6 - Port Signals
Pin 69	VFP - Programming voltage for the Flash EEPROM and required supply for normal operation
Pin 71	PDLC5 or PCAN5 - Port CAN
Pin 73	PDLC3 or PCAN3 - Port CAN
Pin 75	PDLC1 or TxCAN - transmit Port CAN
Pin 77	VSSX - External power and ground, supply to pin drivers
Pin 79	PP7 - Port P
Pin 01	PP5 - Port P
Pin 03	PW3/PP3 - Pulse Width Modulator channel outputs/Port P
Pin 05	PW1/PP1 - Pulse Width Modulator channel outputs/Port P
Pin 07	IOC0/PT0 - input capture and output compare/Port T
Pin 09	IOC2/PT2 - input capture and output compare/Port T
Pin 11	VSS - Internal power and ground
Pin 13	IOC4/PT4 - input capture and output compare/Port T
Pin 15	IOC6/PT6 - input capture and output compare/Port T
Pin 17	SMODN/BKGD - Mode Select/single-Wire Background Mode Pin
Pin 19	ADDR1/DATA1/PB1 - External Address/Data Bus
Pin 21	ADDR3/DATA3/PB3 - External Address/Data Bus/Port B
Pin 23	ADDR5/DATA5/PB5 - External Address/Data Bus/Port B
Pin 25	ADDR7/DATA7/PB7 - External Address/Data Bus/Port B
Pin 27	MODB/IPIPE1/PE6 - Mode Select/Instruction Queue Tracking Signals/Port E
Pin 29	ECLK/PE4 - E-Clock Output/Port E
Pin 31	VDDX - External power and ground, supply to pin drivers
Pin 36	R/(W)'/PE2 - Read/Write/Port E
Pin 38	(XIRQ)'/PE0 - Nonmaskable Interrupt/Port E
Pin 40	ADDR9/DATA9/PA1 - External Address/Data Bus/Port A
Pin 42	ADDR11/DATA11/PA3 - External Address/Data Bus/Port A
Pin 44	ADDR13/DATA13/PA5 - External Address/Data Bus/Port A
Pin 46	ADDR15/DATA15/PA7 - External Address/Data Bus/Port A
Pin 48	VSS - Internal power and ground
Pin 33	EXTAL - External Clock Input
Pin 34	XTAL - Crystal Driver
Pin 50	VRL - Reference voltages for the analog-to-digial converter
Pin 52	PAD1/AN1 - Port AD/Analog inputs
Pin 54	PAD3/AN3 - Port AD/Analog inputs
Pin 56	PAD5/AN5 - Port AD/Analog inputs
Pin 58	PAD7/AN7 - Port AD/Analog inputs
Pin 60	VSSA - Operating voltage and ground for the analog-to-digital converter, allows the suppply voltage to the A/D to be bypassed independently
Pin 62	PS1 - Port Signals
Pin 64	PS3 - Port Signals
Pin 66	PS5 - Port Signals
Pin 68	PS7 - Port Signals
Pin 70	PDLC6 or PCAN6 - Port CAN
Pin 72	PDLC4 or PCAN4 - Port CAN
Pin 74	PDLC2 or PCAN2 - Port CAN
Pin 76	PDLC0 or RxCAN - receive Port CAN
Pin 78	VDDX - External power and ground, supply to pin drivers
Pin 80	PP6 - Port P
Pin 02	PP4 - Port P
Pin 04	PW2/PP2 - Pulse Width Modulator channel outputs/Port P
Pin 06	PW0/PP0 - Pulse Width Modulator channel outputs/Port P
Pin 08	IOC1/PT1 - input capture and output compare/Port T
Pin 10	VDD - Internal power and ground
Pin 12	IOC3/PT3 - input capture and output compare/Port T
Pin 14	IOC5/PT5 - input capture and output compare/Port T
Pin 16	PAI/IOC7/PT7 - Pulse accumulator input/input capture and output compare/Port T
Pin 18	ADDR0/DATA0/PB0 - External Address/Data Bus/Port B
Pin 20	ADDR2/DATA2/PB2 - External Address/Data Bus/Port B
Pin 22	ADDR4/DATA4/PB4 - External Address/Data Bus
Pin 24	ADDR6/DATA6/PB6 - External Address/Data Bus/Port B
Pin 26	(DBE)'/PE7 - Data Bus Enable/Port E
Pin 28	MODA/IPIPE0/PE5 - Mode Select/Instruction Queue Tracking Signals/Port E
Pin 30	VSSX - External power and ground, supply to pin drivers
Pin 32	(RESET)' - reset

It may be helpful to take a look at the ECE Shop's pin Table

Initial Wiring - taking from ECE shop documentation
1. Apply +5V DC to ECE HC912 Chip pin #10, 31, 47, or 78. (Though ECE shop website says just to connect one, they are not interconnected on the module. This can be seen just by looking at their board, none of the connections cross as they run from the HC12 to the connection pins.)
2. Apply GND to HC912 Chip pin #11, 30, 48, or 77. (They are also not interconnected)
3. Establish boot mode as Debut-12 by connecting a 10K resistor from GND to pin #51 and 52.
4. Reseting and initialization is done by connecting pin #32 first to low and then high with a 10K resistor. GND and releasing the pin with the 10K resistor will reset the HC912.
5. Connect the serial RS-232 cable to the computer and the 3 pin female side to the HC912 module. This cable should have came with the HC912 when you got the microprocessor from ECE Shop.

IMPORTANT
Motorola recommends that VFP (pin 18 on Board, 69 on chip) be held at or above VDD at ALL times, otherwise damage to the chip can occur. They don't say why, but they also recommend that you don't leave it at 12V when you aren't programming it either. Connect it to VDD (5V) when you are running it normally.

This page created by: CJ Oster and Joe Ngai

Last Modified: April 17, 2003

Please contact Professor Gary Swenson (swenson1@uiuc.edu) to learn more about the course, or contact the webmaster (wiegert@uiuc.edu) with questions or comments about the web site. Web Site designed by Purvesh Thakker.