
6
6384DS–ATARM–13-Jan-10
AT91SAM9G20 Summary
Reset/Test
NRST
Microcontroller Reset
I/O
Low
Pull-up resistor
TST
Test Mode Select
Input
Pull-down resistor. Accepts
between 0V and VDDBU.
BMS
Boot Mode Select
Input
No pull-up resistor
BMS = 0 when tied to GND.
BMS = 1 when tied to VDDIOP.
Debug Unit - DBGU
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
Advanced Interrupt Controller - AIC
IRQ0 - IRQ2
External Interrupt Inputs
Input
FIQ
Fast Interrupt Input
Input
PIO Controller - PIOA - PIOB - PIOC
PA0 - PA31
Parallel IO Controller A
I/O
Pulled-up input at reset
PB0 - PB31
Parallel IO Controller B
I/O
Pulled-up input at reset
PC0 - PC31
Parallel IO Controller C
I/O
Pulled-up input at reset
External Bus Interface - EBI
D0 - D31
Data Bus
I/O
Pulled-up input at reset
A0 - A25
Address Bus
Output
0 at reset
NWAIT
External Wait Signal
Input
Low
Static Memory Controller - SMC
NCS0 - NCS7
Chip Select Lines
Output
Low
NWR0 - NWR3
Write Signal
Output
Low
NRD
Read Signal
Output
Low
NWE
Write Enable
Output
Low
NBS0 - NBS3
Byte Mask Signal
Output
Low
CompactFlash Support
CFCE1 - CFCE2
CompactFlash Chip Enable
Output
Low
CFOE
CompactFlash Output Enable
Output
Low
CFWE
CompactFlash Write Enable
Output
Low
CFIOR
CompactFlash IO Read
Output
Low
CFIOW
CompactFlash IO Write
Output
Low
CFRNW
CompactFlash Read Not Write
Output
CFCS0 - CFCS1
CompactFlash Chip Select Lines
Output
Low
Table 3-1.
Signal Description List (Continued)
Signal Name
Function
Type
Active
Level
Comments