Serial Port Complete - Latest Microcontroller projects

An RS-485 Network



 

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The network encodes data in ASCII Hex format. Chapter 2 showed .NET code

for converting between binary and ASCII Hex bytes. Microcontroller code can

perform these conversions as well.

The byte_to_ascii_hex function converts a byte (value_to_convert) to two

ASCII hex characters that represent the byte’s value (upper_nibble and

lower_nibble):

 byte_to_ascii_hex:

' Represent the byte variable value_to_convert as

' ASCII Hex characters upper_nibble and lower_nibble.

upper_nibble = (value_to_convert & $f0) >> 4

if ((upper_nibble >= 0) AND (upper_nibble <= 9)) then

upper_nibble = upper_nibble + 48

else

' The value is between 10 (a) and 15 (f).

upper_nibble = upper_nibble + 87

endif

lower_nibble = (value_to_convert & $0f)

if ((lower_nibble >= 0) AND (lower_nibble <= 9)) then

lower_nibble = lower_nibble + 48

else

' The value is between 10 (a) and 15 (f).

lower_nibble = lower_nibble + 87

endif

return