MC68HC908GR4MP datasheet(156/286 Pages) FREESCALE

156 / 286 page

Input/Output Ports (I/O)

MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7

156

Freescale Semiconductor

RxD — SCI Receive Data Input

The PTE1/RxD pin is the receive data input for the SCI module. When the enable SCI bit, ENSCI, is

clear, the SCI module is disabled, and the PTE1/RxD pin is available for general-purpose I/O. See

Chapter 18 Serial Communications Interface (SCI).

TxD — SCI Transmit Data Output

The PTE0/TxD pin is the transmit data output for the SCI module. When the enable SCI bit, ENSCI, is

clear, the SCI module is disabled, and the PTE0/TxD pin is available for general-purpose I/O. See

Chapter 18 Serial Communications Interface (SCI).

16.6.2 Data Direction Register E

Data direction register E (DDRE) determines whether each port E pin is an input or an output. Writing a 1

to a DDRE bit enables the output buffer for the corresponding port E pin; a 0 disables the output buffer.

DDRE1 and DDRE0 — Data Direction Register E Bits

These read/write bits control port E data direction. Reset clears DDRE1 and DDRE0, configuring all

port E pins as inputs.

1 = Corresponding port E pin configured as output

0 = Corresponding port E pin configured as input

NOTE

Avoid glitches on port E pins by writing to the port E data register before

changing data direction register E bits from 0 to 1.

Figure 16-19 shows the port E I/O logic.

Figure 16-19. Port E I/O Circuit

Address:

$000C

Bit 7

654321

Bit 0

Read:

000000

DDRE1

DDRE0

Write:

Reset:

00000000

= Unimplemented

Figure 16-18. Data Direction Register E (DDRE)

READ DDRE ($000C)

WRITE DDRE ($000C)

RESET

WRITE PTE ($0008)

READ PTE ($0008)

PTEx

DDREx

PTEx

MC68HC908GR4MP Datasheet(PDF) 156 Page - Freescale Semiconductor, Inc

MC68HC908GR4MP Datasheet(HTML) 156 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL