514Companion Products
© Tibbo Technology Inc.
Reset, active LOW (input*).
SPI port, data out (output*, must be connected to DI of
Tibbo module).
SPI port, clock (input*).
* Of the GA1000.
Connecting GA1000 to Tibbo Devices
GA1000 interface
The GA1000 communicates with Tibbo devices through an SPI interface. Your device
will control the GA1000 through five GPIO lines:
·
CS -- SPI bus, chip select (active low);
·
CLK -- SPI bus, clock;
·
DI -- SPI bus, data in (must be connected to the DO line of the host);
·
DO -- SPI bus, data out (must be connected to the DI line of the host);
·
RST -- reset (active low). This line can be eliminated -- see below for details.
On all devices except the EM500, do not forget to configure CS, CLK, DO, and
RST as outputs. DI must be configured as input. The wln. object won't do this
automatically. GPIO configuration is not necessary on the EM500, whose lines
are bidirectional.
Providing hardware reset
The wln. object directly controls CS, CLK, DI, and DO lines. Your application,
however, must take care of the proper hardware reset for the GA1000. There are
two methods for doing this:
·
Use a dedicated GPIO line to act as the RST line of the GA1000 interface (shown
on diagram A below).
·
Use 2 NAND gates to combine CS and CLK signals and produce the reset signal for
the GA1000 (shown on diagram B). This approach takes advantage of the fact
that during SPI communications, CLK line will never be LOW while the CS line is
HIGH. Schematic diagram on figure B generates reset when CS=HIGH and
CLK=LOW. This way you save one GPIO line of your programmable module.
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