Microchip Technology AC164145 Manuel D’Utilisation
Demonstration
© 2011 Microchip Technology Inc.
DS75019A-page 21
PLM_FRAMING
This setting enables the low-level framing and is disabled by default. If enabled, the
demodulator will seek frames with following:
• Preamble (length depends on the PLM_PRE_SIZE configuration setting)
• Start Of Frame (as set in the PLM_SOF configuration setting)
• Length (1 to 253, length, SOF and data inclusive)
• Data bytes
demodulator will seek frames with following:
• Preamble (length depends on the PLM_PRE_SIZE configuration setting)
• Start Of Frame (as set in the PLM_SOF configuration setting)
• Length (1 to 253, length, SOF and data inclusive)
• Data bytes
PLM_SOF
The Start of Frame (SOF) character. This setting is used only if low-level framing is
enabled.
enabled.
PLM_FEC
This setting enables the Forward Error Correction (FEC) feature. Please note that the
Viterbi algorithm used for the FEC feature requires significant processing power,
especially at higher code constraint lengths.
Viterbi algorithm used for the FEC feature requires significant processing power,
especially at higher code constraint lengths.
PLM_QUALITY_MEASURE
This setting enables received signal quality estimation and determines a 16-bit quality
metric calculated during the initial bytes after the last byte synchronization has been
found. The metric is an average value of absolute values of demodulated signal sam-
ples, taken in the instance of bit decisions during the first 16 bytes after byte
synchronization has been found. A value greater then 0x7F00 means perfect quality.
metric calculated during the initial bytes after the last byte synchronization has been
found. The metric is an average value of absolute values of demodulated signal sam-
ples, taken in the instance of bit decisions during the first 16 bytes after byte
synchronization has been found. A value greater then 0x7F00 means perfect quality.
PLM_LOCAL_ECHO
This setting, if enabled, allows the modem to receive its own transmissions.
PLM_DEBUG_MODE
This setting enables various debugging modes and normally should be off (set to
DEBUG OFF). The other modes supported are:
• Signal Logging mode, where signal samples on various demodulation stages can
DEBUG OFF). The other modes supported are:
• Signal Logging mode, where signal samples on various demodulation stages can
be saved in a circular buffer
• Performance Measurement mode in which a GPIO pin (RG0) is set high
whenever the processor is executing low-level modem code
PLM_RAM_SAVING
If enabled, this setting causes the modem code to use less RAM (reduced by a third)
at a cost of consuming more processing power (2 to 4 MIPS). In case this option is
enabled, a processing buffer size must also be selected by manually setting
PLM_DEM_BLOCK_LEN. The smaller the buffer, the smaller the amount of RAM used;
however, the performance hit is more significant.
at a cost of consuming more processing power (2 to 4 MIPS). In case this option is
enabled, a processing buffer size must also be selected by manually setting
PLM_DEM_BLOCK_LEN. The smaller the buffer, the smaller the amount of RAM used;
however, the performance hit is more significant.
PLM_ADC
This setting allows the selection of the ADC, in case the dsPIC33F DSC device used
has more than one ADC module.
has more than one ADC module.
PLM_USE_DMA
This setting, if set to ‘
1
’, causes the code to be compiled with DMA support. Unless
there are good reasons not to (e.g., no DMA support in the selected CPU model), DMA
should be used for best performance.
should be used for best performance.