Hardware Connections
I/O pin
I/O pin
ENABLEPA
ENABLELNA
STROBE
I/O pin
RSSIC
I/O pin
DATACLK
Timer channel clock input
RSSIOUT
I/O pin
MCU
ECHO
CONFB
SEB
I/O pin
I/O pin
TX DATA
Timer channel output
MOSI
MISO
SCLK
MOSI
MISO
SCLK
SS
Required
Optional
Figure 4. Echo Hardware Connections
A brief description of each connection follows:
•
MOSI, MISO, SCLK, and SS—SPI connections allowing configuration information to be sent to
Echo and received data to be sent back to the MCU. SS must be held low when the MCU is an SPI
slave and awaiting data from Echo. In many systems this can be grounded with a pulldown resistor.
•
TX DATA—The MOSI pin on Echo has dual functionality. When Echo is in receive mode,
received data is output on the SPI to the MCU. When in transmit mode, the MOSI pin directly
receives the waveform to be modulated. The driver generates the Manchester encoded waveform
using a timer channel, and the corresponding channel pin is connected to MOSI when in transmit
mode.
•
•
SEB—Enables the digital interface on Echo. When SEB is high, the MOSI, MISO, and SCLK pins
on Echo are high impedance, allowing other devices to be used on the SPI.
CONFB—Resets Echo into configuration mode to allow access to Echo’s internal registers.
Software Drivers for MC33696, Rev. 1
Freescale Semiconductor
7
FREESCALE [ Freescale ]
