Rainbow Electronics ATmega32L - Manual (Page 59)

59
ATmega32(L)
2503C–AVR–10/02
• TCK – Port C, Bit 2
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.
• SDA – Port C, Bit 1
SDA, Two-wire Serial Interface Data: When the TWEN bit in TWCR is set (one) to
enable the Two-wire Serial Interface, pin PC1 is disconnected from the port and
becomes the Serial Data I/O pin for the Two-wire Serial Interface. In this mode, there is
a spike filter on the pin to suppress spikes shorter than 50 ns on the input signal, and the
pin is driven by an open drain driver with slew-rate limitation. When this pin is used by
the Two-wire Serial Interface, the pull-up can still be controlled by the PORTC1 bit.
• SCL – Port C, Bit 0
SCL, Two-wire Serial Interface Clock: When the TWEN bit in TWCR is set (one) to
enable the Two-wire Serial Interface, pin PC0 is disconnected from the port and
becomes the Serial Clock I/O pin for the Two-wire Serial Interface. In this mode, there is
a spike filter on the pin to suppress spikes shorter than 50 ns on the input signal, and the
pin is driven by an open drain driver with slew-rate limitation. When this pin is used by
the Two-wire Serial Interface, the pull-up can still be controlled by the PORTC0 bit.
Table 29 and Table 30 relate the alternate functions of Port C to the overriding signals
shown in Figure 26 on page 52.
Table 29. Overriding Signals for Alternate Functions in PC7..PC4
Signal
Name
PC7/TOSC2 PC6/TOSC1 PC5/TDI PC4/TDO
PUOE AS2 AS2 JTAGEN JTAGEN
PUOV 0 0 1 0
DDOE AS2 AS2 JTAGEN JTAGEN
DDOV 0 0 0 SHIFT_IR + SHIFT_DR
PVOE 0 0 0 JTAGEN
PVOV 0 0 0 TDO
DIEOE AS2 AS2 JTAGEN JTAGEN
DIEOV 0 0 0 0
DI – – – –
AIO T/C2 OSC OUTPUT T/C2 OSC INPUT TDI –