User Guide

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MAXTXRETRY - Maximum Transmit Retries
Volatile Address = 0x52; Non-Volatile Address = 0x07
The value in the MAXTXRETRY register sets the number of transmission
retries performed if an acknowledgement is not received. If an
acknowledgement is not received after the last retry, exception EX_
NORFACK is raised. Figure 41 shows examples of the command.
The time between retries depends on the current baud rate. Figure 42
shows the time between retries based on baud rate. The elapsed transmit
and acknowledgment time is (retries+1) × (PacketTransmitTime + Timeout).
Figure 41: HumPRC
TM
Series Maximum Transmit Retries Command and Response
HumPRC
TM
Series Acknowledgement Timeout Times
Baud Rate Timeout Time
9,600 50ms
19,200 50ms
38,400 30ms
57,600 30ms
115,200 30ms
Figure 42: HumPRC
TM
Series Acknowledgement Timeout Times
HumPRC
TM
Series Maximum Transmit Retries
Read Command Read Response
Header Size Escape Address ACK Address Value
0xFF 0x02 0xFE
0x52
0x07
0x06
0x52
0x07
V
Write Command
Header Size Address Value
0xFF 0x02
0x52
0x07
V
ENCRC - CRC Enable
Volatile Address = 0x53; Non-Volatile Address = 0x08
The protocol includes a Cyclic Redundancy Check (CRC) on the received
unencrypted packets to make sure that there are no errors. Encrypted
packets use a key-based error detection method. Any packets with errors
are discarded and not output on the UART. This feature can be disabled
if it is desired to perform error checking outside the module. Set the
ENCRC register to 0x01 to enable CRC checking, or 0x00 to disable it. The
default CRC mode setting is enabled. Figure 43 shows examples of the
commands and Figure 44 shows the available values.
Although disabling CRC checking allows receiving packets with errors
in the payload, errors in the header can still prevent packets from being
output by the module.
BCTRIG - UART Byte Count Trigger
Volatile Address = 0x54; Non-Volatile Address = 0x09
This register selects options for transferring packet data in the HumPRO
TM
Series. These options are controlled automatically by the HumPRC
TM
application and do not have any effect on its operation.
HumPRC
TM
Series CRC Enable Register Settings
V Mode
0x00 CRC Disabled
0x01 CRC Enabled
Figure 43: HumPRC
TM
Series CRC Enable Command and Response
Figure 44: HumPRC
TM
Series CRC Enable Register Settings
HumPRC
TM
Series CRC Enable
Read Command Read Response
Header Size Escape Address ACK Address Value
0xFF 0x02 0xFE
0x53
0x08
0x06
0x53
0x08
V
Write Command
Header Size Address Value
0xFF 0x02
0x53
0x08
V