Toradex Colibri - Unused Memory Bus Signals Termination; Gpio; Preferred GPIO Signals; Unused GPIO Termination

Colibri Carrier Board Design Guide
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Colibri
Pin
Colibri
Signal Name
I/O
Type
Power
Rail
Description
128
BUS_DQM1
O
CMOS
3.3V
Byte Enable Mask, corresponds to D[15:8]
130
BUS_DQM2
O
CMOS
3.3V
Byte Enable Mask, corresponds to D[23:16]
132
BUS_DQM3
O
CMOS
3.3V
Byte Enable Mask, corresponds to D[31:24]
105
BUS_nCS0
O
CMOS
3.3V
Chip select signals, all required chip select signals should be
pulled up on the carrier board.
107
BUS_nCS1
O
CMOS
3.3V
106
BUS_nCS2
O
CMOS
3.3V
91
BUS_nOE
O
CMOS
3.3V
Output Enable
99
BUS_nPWE
O
CMOS
3.3V
Buffered Write Enable
89
BUS_nWE
O
CMOS
3.3V
Write Enable
93
BUS_RDnWR
O
CMOS
3.3V
Buffered Write Enable
95
BUS_RDY
I
CMOS
3.3V
Ready/Busy/Wait signal
Table 23: Memory Bus Signals
2.17.2 Unused Memory Bus Signals Termination
All unused memory bus signals can be left unconnected. On the Colibri PXA270, the memory bus
interface is also used on the module for connecting the RAM, flash, and Ethernet controller.
Therefore, the bus signal pins cannot be used for any other purpose on this module. It might be
possible to use the unused bus signals as GPIO or for other alternative functions on other modules.
2.18 GPIO
Many interface pins can also be used as a general-purpose input-output pin (GPIO) for alternative
functions. Theoretically, any unused interface pin that serves a GPIO function can be used. Since
some interface pins do not provide GPIO functionality on certain Colibri modules, there is a list of
preferred GPIO pins. For compatibility reasons, we recommend using the first pin on this list.
Please note that there might be additional restrictions in using the GPIO functions on certain
modules. For example, two pins share the same GPIO instance and cannot be used independently
of each other on some modules. More information can be found in the datasheet of the module.
2.18.1 Preferred GPIO Signals
Colibri
Pin
I/O
Type
Power
Rail
Description
19, 21, 23, 25, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 38, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52,
53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,
66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 78, 79,
80, 81, 82, 85, 86, 88, 90, 92, 95, 97, 98, 99, 100,
101, 102, 103, 104, 105, 106, 107, 127, 129, 131,
133, 135, 137, 190, 192, 194, 196
I/O
CMOS
3.3V
General-purpose GPIO
Table 24: Dedicated GPIO Signals
2.18.2 Unused GPIO Termination
The GPIO signals do not need to be terminated if they are not in use.