Freescale Semiconductor MC68HC908MR32 manual Port F Data Register, Data Direction Register F

Input/Output (I/O) Ports (PORTS)

10.7 Port F

Port F is a 6-bit, special function port that shares four of its pins with the serial peripheral interface module (SPI) and two pins with the serial communications interface (SCI).

10.7.1 Port F Data Register

The port F data register (PTF) contains a data latch for each of the six port F pins.

Address:

Read:

Write:

Reset:

$0009
Bit 7	6	5	4	3	2	1	Bit 0
0	0	PTF5	PTF4	PTF3	PTF2	PTF1	PTF0
R	R

Unaffected by reset

R= Reserved

Figure 10-16. Port F Data Register (PTF)

PTF[5:0] — Port F Data Bits

These read/write bits are software programmable. Data direction of each port F pin is under the control of the corresponding bit in data direction register F. Reset has no effect on PTF[5:0].

NOTE

Data direction register F (DDRF) does not affect the data direction of port F pins that are being used by the SPI or SCI module. However, the DDRF bits always determine whether reading port F returns the states of the latches or the states of the pins.

10.7.2 Data Direction Register F

Data direction register F (DDRF) determines whether each port F pin is an input or an output. Writing a logic 1 to a DDRF bit enables the output buffer for the corresponding port F pin; a logic 0 disables the output buffer.

Address:

Read:

Write:

Read:

$000D
Bit 7	6	5	4	3	2	1	Bit 0
0	0	DDRF5	DDRF4	DDRF3	DDRF2	DDRF1	DDRF0
R	R
		0	0	0	0	0	0

R= Reserved

Figure 10-17. Data Direction Register F (DDRF)

DDRF[5:0] — Data Direction Register F Bits

These read/write bits control port F data direction. Reset clears DDRF[5:0], configuring all port F pins as inputs.

1 = Corresponding port F pin configured as output

0 = Corresponding port F pin configured as input

NOTE

Avoid glitches on port F pins by writing to the port F data register before changing data direction register F bits from 0 to 1.

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

110 Freescale Semiconductor