Alternate Functions of Port F
The Port F has an alternate function as analog input for the ADC as shown in Table 51.
If some Port F 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. If the
JTAG interface is enabled, the pull-up resistors on pins PF7(TDI), PF5(TMS), and
PF4(TCK) will be activated even if a Reset occurs.
Table 51. Port F Pins Alternate Functions
Port Pin
PF7
Alternate Function
ADC7/TDI (ADC input channel 7 or JTAG Test Data Input)
ADC6/TDO (ADC input channel 6 or JTAG Test Data Output)
ADC5/TMS (ADC input channel 5 or JTAG Test Mode Select)
ADC4/TCK (ADC input channel 4 or JTAG Test ClocK)
ADC3 (ADC input channel 3)
PF6
PF5
PF4
PF3
PF2
ADC2 (ADC input channel 2)
PF1
ADC1 (ADC input channel 1)
PF0
ADC0 (ADC input channel 0)
• TDI, ADC7 – Port F, Bit 7
ADC7, Analog to Digital Converter, Channel 7.
TDI, JTAG Test Data In: Serial input data to be shifted in to the Instruction Register or
Data Register (scan chains). When the JTAG interface is enabled, this pin can not be
used as an I/O pin.
• TDO, ADC6 – Port F, Bit 6
ADC6, Analog to Digital Converter, Channel 6.
TDO, JTAG Test Data Out: Serial output data from Instruction Register or Data Regis-
ter. When the JTAG interface is enabled, this pin can not be used as an I/O pin.
The TDO pin is tri-stated unless TAP states that shift out data are entered.
• TMS, ADC5 – Port F, Bit 5
ADC5, Analog to Digital Converter, Channel 5.
TMS, JTAG Test Mode Select: This pin is used for navigating through the TAP-controller
state machine. When the JTAG interface is enabled, this pin can not be used as an I/O
pin.
• TCK, ADC4 – Port F, Bit 4
ADC4, Analog to Digital Converter, Channel 4.
TCK, JTAG Test Clock: JTAG operation is synchronous to TCK. When the JTAG inter-
face is enabled, this pin can not be used as an I/O pin.
100
ATmega640/1280/1281/2560/2561
2549A–AVR–03/05
ATMEL [ ATMEL ]
