Rainbow Electronics ATmega32L - Manual (Page 54)

54
ATmega32(L)
2503C–AVR–10/02
Special Function I/O Register
– SFIOR
• Bit 2 – PUD: Pull-up disable
When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn
and PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01).
See “Configuring the Pin” on page 48 for more details about this feature.
Alternate Functions of Port A Port A has an alternate function as analog input for the ADC as shown in Table 22. If
some Port A pins are configured as outputs, it is essential that these do not switch when
a conversion is in progress. This might corrupt the result of the conversion.
Table 23 and Table 24 relate the alternate functions of Port A to the overriding signals
shown in Figure 26 on page 52.
Bit 7 6 5 4 3 2 1 0
ADTS2 ADTS1 ADTS0 – ACME PUD PSR2 PSR10 SFIOR
Read/Write R/W R/W R/W R R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Table 22. Port A Pins Alternate Functions
Port Pin Alternate Function
PA7 ADC7 (ADC input channel 7)
PA6 ADC6 (ADC input channel 6)
PA5 ADC5 (ADC input channel 5)
PA4 ADC4 (ADC input channel 4)
PA3 ADC3 (ADC input channel 3)
PA2 ADC2 (ADC input channel 2)
PA1 ADC1 (ADC input channel 1)
PA0 ADC0 (ADC input channel 0)
Table 23. Overriding Signals for Alternate Functions in PA7..PA4
Signal Name PA7/ADC7 PA6/ADC6 PA5/ADC5 PA4/ADC4
PUOE 0 0 0 0
PUOV 0 0 0 0
DDOE 0 0 0 0
DDOV 0 0 0 0
PVOE 0 0 0 0
PVOV 0 0 0 0
DIEOE 0 0 0 0
DIEOV 0 0 0 0
DI – – – –
AIO ADC7 INPUT ADC6 INPUT ADC5 INPUT ADC4 INPUT