Echo Driver Configuration
ECHO_CRYSTAL_FREQUENCY
Description: This defines the speed (in Hz) of the crystal used by Echo. Typical values at supported RF
frequencies are:
315 MHz—17581400
434 MHz—24190660
868 MHz—24161390
Values:
Integer in the range 0–100000000
#define ECHO_CRYSTAL_FREQUENCY 24190660 /* Crystal frequency (in Hz) */
Example:
11.1.4 Buffering Parameters
ECHO_MAX_DATA_SIZE
Description: This defines the maximum number of data bytes that can be transferred. This is used to
allocate buffer space for both transmitting and receiving messages.
Values:
1–127
#define ECHO_MAX_DATA_SIZE 127 /* Max length of data field in msg */
Example:
ECHO_RX_BUF_COUNT
Description: This defines the number of receive buffers that are allocated to store received messages in.
Storage space allocated to external receive buffers is:
(ECHO_MAX_DATA_SIZE+2)*ECHO_RX_BUF_COUNT.
Values:
Minimum of 1; maximum limited by size of RAM available.
#define ECHO_RX_BUF_COUNT 4 /* Number of Rx buffers to allocate */
Example:
11.1.5 Miscellaneous
ECHO_SWITCH_LEVEL
Description: Specifies the value to place Echo’s SL bit; this sets the active level of SWITCH output pin.
Values:
0 = Rx low, Tx high
1 = Tx low, Rx high
#define ECHO_SWITCH_LEVEL 0 /* Set active level of SWITCH o/p pin */
Example:
Software Drivers for MC33696, Rev. 1
32
Freescale Semiconductor
FREESCALE [ Freescale ]
