Specifications
Freescale MC13224 chip
This section applies if you are running SNAP on a Freescale MC13224 chip in your own hardware. If
you instead are running SNAP on a Synapse SM700 module, refer also to the section following this
one.
IO pins
The MC13224 supports 64 GPIO input/output pins, referenced as GPIO_0 through CPIO_63.
Wakeup pins
Four pins, GPIO_26 through GPIO_29, can be configured to wake the module from sleep. Note that
these pins automatically become inputs when entering sleep. Four other pins, GPIO_22 through
GPIO_25 automatically become outputs when entering sleep (this behavior is not under software
control).
Analog inputs
Eight pins support ADC usage. GPIO_30 through GPIO_37 can be read as ADC0 through ADC7,
respectively. The ADCs can be read against VCC or either of two external reference voltages.
UART0
Four pins support UART 0. GPIO_14 and GPIO_15 perform as TX and RX, respectively, and
GPIO_16 and GPIO_17 perform as CTS and RTS, respectively. If you do not need RTS/CTS signals,
then those pins are available for other uses. The serial port requires 8 data bits, and ignores any other
value set in the initUart() function. Each serial port supports 1 or 2 stop bits, and Odd, Even, or No
parity.
UART1
Four pins support UART 1. GPIO_18 and GPIO_19 perform as TX and RX, respectively, and
GPIO_20 and GPIO_21 perform as CTS and RTS, respectively. If you do not need RTS/CTS signals,
then those pins are available for other uses. The serial port requires 8 data bits, and ignores any other
value set in the initUart() function. Each serial port supports 1 or 2 stop bits, and Odd, Even, or No
parity.
SPI
Three pins can optionally be used for SPI. GPIO_5, GPIO_6, and GPIO_7 are MISO, MOSI, and
SCK, respectively.
NOTE – these are not hardware SPI pins. SNAPpy SPI is done via software emulation.
You will also need one “SPI Chip Select” pin per external SPI device. Any available IO pin can be
used for this purpose.
I
2
C
Two pins can optionally be used for I
2
C. GPIO_12 and GPIO_13 are SCL and SDA, respectively.
NOTE – these are not hardware I
2
C pins. SNAPpy I
2
C is done via software emulation.
SNAP Reference Manual Document Number 600-0007K Page 177 of 202