Microchip Technology AC164142 User Manual
Consumer-band BPSK 7.2 kbps PLM PICtail™ Plus Daughter Board User’s Guide
DS70656A-page 24
© 2011 Microchip Technology Inc.
The memory and MIPS requirements for the modem software for different baud rates
(with DMA and RAM-saving options enabled) are listed in
(with DMA and RAM-saving options enabled) are listed in
TABLE 3-1:
MEMORY AND MIPS REQUIREMENTS FOR THE MODEM
3.1.6
Developing Custom Applications
An application template has been provided to ease the development of customized
PLM applications. The application template can be downloaded from the
Consumer-band BPSK 7.2 kbps PLM PICtail Plus Daughter Board web site at:
PLM applications. The application template can be downloaded from the
Consumer-band BPSK 7.2 kbps PLM PICtail Plus Daughter Board web site at:
.
By default, the software for the daughter board is designed to operate on a carrier
frequency of 129.6 kHz. However, if required, the software can be modified to operate
at a different carrier frequency. In this case, the following need to be taken into
consideration:
• The hardware provided in the kit is designed to operate at a carrier frequency of
frequency of 129.6 kHz. However, if required, the software can be modified to operate
at a different carrier frequency. In this case, the following need to be taken into
consideration:
• The hardware provided in the kit is designed to operate at a carrier frequency of
129.6 kHz. Changing the carrier frequency in software will require modifications to
the hardware components, specifically the components that decide the filter cutoff
frequencies
the hardware components, specifically the components that decide the filter cutoff
frequencies
• It is necessary for the carrier frequency to be an integral multiple of the baud rate:
Carrier frequency, F
C
= k * baud, k
ϵ Integer
• Lower carrier frequencies result in lower maximum possible data rates
• Carrier frequency or baud rate changes outside the combinations provided in the
• Carrier frequency or baud rate changes outside the combinations provided in the
include file (
...\modem\bpsk\bpsk_filter.inc
) will require recalculation of
digital filter coefficients
• Increasing carrier frequency increases the MIPS requirement for the modem soft-
ware. For this reason, the carrier frequency must be well within the CPU’s useful
performance limit. The modem software requires approximately 0.234 to 0.303
MIPS/kHz of carrier frequency
performance limit. The modem software requires approximately 0.234 to 0.303
MIPS/kHz of carrier frequency
Baud Rate
RAM (Bytes)
Flash (Bytes)
MIPS
1200
700
2709
33.5
2400
412
2709
33.6
3600
316
2709
33.7
4800
268
2709
33.9
5400
252
2709
33.9
7200
220
2709
34.1