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GR716-DS-UM, May 2019, Version 1.29
32
www.cobham.com/gaisler
GR716
2.4
Signal Overview
The GR716 microcontroller has 64 external general purpose user input and outputs, 6 LVDS trans-
ceivers and dedicated SPI memory interface. Almost all 64 external inputs and outputs and LVDS
transceivers have multiple functionality. Functionality is selected by the application software during
startup and configuration. During startup i.e. after reset all user input and outputs are configured as
inputs.
LVDS transmitters are disabled after reset and only enabled if SpaceWire or SPI for Space is enabled.
2.5
I/O switch matrix overview
This section provides a introduction to the I/O switch matrix and gives a presentation to the pre-
defined set of pin configuration.
The I/O switch matrix provides access to several I/O units. When an interface is not activated, its pins
automatically become general purpose I/O. After reset, all I/O switch matrix pins are defined as inputs
until programmed otherwise. Configuration and assigning of functions to external I/O is flexible and
is controlled by software via registers described in section 7.1.
Figure 5 shows an overview of how the various I/O units are connected to the I/O switch matrix.
Figure 5.
MCTRL
SPI
UART
ADCDAC
I2C
GPIO
SPW
CAN
PWRX
PWTX
1553B
OnChip
ADCDAC
GPREG
Mixed Signal General Puropse
Inputs and outputs
SPW
SPI
For Space
LVDS for
SpaceWire or
SPI-for-Space
192K RAM
SPI Boot
ROM
IRQ
TIMERS
LDO
POR
& BO
PLL
LSTAT
DSU
LEON3
XO
Power
supply
Oscillator
Power
Sense
and
reset
SpaceWire
clock and
PLL status
DSU
enable,
break and
status
External
SPI Boot
ROM
Architectural block diagram showing connections to the I/O switch matrix
Table 2.6 shows a listing of all external CMOS pins in the I/O switch matrix and what functions can
be assign to external pins. Table 2.6 also shows configuration registers to assign specific function or
pin to external I/O. To assign a specific function or pin to an external interface the “column” value
should be written into the table ’row’ I/O configuration register and bit field. E.g. n register
SYS.CFG.GP0.GP5 described in section 7.1.