Datasheet

33
42023ES–SAM–07/2013
ATSAM4L8/L4/L2
Note: 1. See “Power and Startup Considerations” section.
3.4 I/O Line Considerations
3.4.1 SW/JTAG Pins
The JTAG pins switch to the JTAG functions if a rising edge is detected on TCK low after the
RESET_N pin has been released. The TMS, and TDI pins have pull-up resistors when used as
JTAG pins. The TCK pin always has pull-up enabled during reset. The JTAG pins can be used
as GPIO pins and multiplexed with peripherals when the JTAG is disabled. Refer to Section
3.2.3 ”JTAG Port Connections” on page 28 for the JTAG port connections.
For more details, refer to Section 1.1 ”Enhanced Debug Port (EDP)” on page 3.
3.4.2 RESET_N Pin
The RESET_N pin is a schmitt input and integrates a permanent pull-up resistor to VDDIN. As
the product integrates a power-on reset detector, the RESET_N pin can be left unconnected in
case no reset from the system needs to be applied to the product.
3.4.3 TWI Pins
When these pins are used for TWI, the pins are open-drain outputs with slew-rate limitation and-
inputs with inputs with spike-filtering. When used as GPIO-pins or used for other peripherals, the
pins have the same characteristics as GPIO pins.
3.4.4 GPIO Pins
All the I/O lines integrate a pull-up/pull-down resistor and slew rate controller. Programming
these features is performed independently for each I/O line through the GPIO Controllers. After
reset, I/O lines default as inputs with pull-up and pull-down resistors disabled and slew rate
enabled.
3.4.5 High-drive Pins
The six pins PA02, PB00, PB01, PC04, PC05 and PC06 have high-drive output capabilities.
Refer to Section 9.6.2 ”High-drive I/O Pin : PA02, PC04, PC05, PC06” on page 114 for electrical
characteristics.
3.4.6 USB Pins
When these pins are used for USB, the pins are behaving according to the USB specification.
When used as GPIO pins or used for other peripherals, the pins have the same behavior as
other normal I/O pins, but the characteristics are different. Refer to Section 9.6.3 ”USB I/O Pin :
PA25, PA26” on page 115 for electrical characteristics.
These pins are compliant to USB standard only when VDDIO power supply is 3.3
V nominal.
PA31 - PA00 Parallel I/O Controller I/O Port A I/O
PB15 - PB00 Parallel I/O Controller I/O Port B I/O
PC31 - PC00 Parallel I/O Controller I/O Port C I/O
Table 3-8. Signal Descriptions List (Sheet 4 of 4)
Signal Name Function Type
Active
Level Comments