Rainbow-electronics ATmega103L User Manual download pdf (Page 87)

ATmega603/103

Port E

Port E is an 8-bit bi-directional I/O port with internal pull-up resistors.

Three I/O memory address locations are allocated for the Port E, one each for the Data Register - PORTE, $03($23), Data

Direction Register - DDRE, $02($22) and the Port E Input Pins - PINE, $01($21). The Port E Input Pins address is read

only, while the Data Register and the Data Direction Register are read/write.

The Port E output buffers can sink 20 mA. As inputs, Port E pins that are externally pulled low will source current if the pull-

up resistors are activated.

All Port E pins have alternate functions as shown in the following table:

When the pins are used for the alternate function the DDRE and PORTE register has to be set according to the alternate

function description.

Port E Data Register - PORTE

Port E Data Direction Register - DDRE

Port E Input Pins Address - PINE

The Port E Input Pins address - PINE - is not a register, and this address enables access to the physical value on each Port

E pin. When reading PORTE, the Port E Data Latch is read, and when reading PINE, the logical values present on the pins

are read.

Table 34. Port E Pins Alternate Functions

Port Pin Alternate Function

PE0 PDI/RXD (Programming Data Input or UART Receive Pin)

PE1 PDO/TXD (Programming Data Output or UART Transmit Pin)

PE2 AC+ (Analog Comparator Positive Input)

PE3 AC- (Analog Comparator Negative Input)

PE4 INT4 (External Interrupt4 Input)

PE5 INT5 (External Interrupt5 Input)

PE6 INT6 (External Interrupt6 Input)

PE7 INT7 (External Interrupt7 Input)

Bit 76543210

$03 ($23) PORTE7 PORTE6 PORTE5 PORTE4 PORTE3 PORTE2 PORTE1 PORTE0 PORTE

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial value00000000

Bit 76543210

$02 ($22) DDE7 DDE6 DDE5 DDE4 DDE3 DDE2 DDE1 DDE0 DDRE

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial value00000000

Bit 76543210

$01 ($21) PINE7 PINE6 PINE5 PINE4 PINE3 PINE2 PINE1 PINE0 PINE

Read/WriteRRRRRRRR

Initial value Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z

1 2 ... 82 83 84 85 86 87 88 89 90 91 92 ... 125 126

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Rainbow-electronics ATmega103L User Manual Page 87