FotS

Converts a decimal number to its BCD equivalent.

e.g. 27 is returned as &h27 (39 decimal)

This is useful for writing to device registers that require BCD to hold a value rather than binary. An example here is the registers inside popular Real Time Clock chips (DS3231, etc). Consider the day-of-month register. The bottom nibble holds the units and the top nibble holds the tens. A value of 31 decimal cannot be written directly into the register as this would result in the value &h1F being written - which is illegal.

The following function takes a decimal value and returns the same positional digits as a hex number, so in the example above, 31 decimal would be returned as 31 hex (49 decimal). this would result in the legal values of 3 being written to the top nibble of the register and 1 written to the bottom nibble.

Option default integer
\\
For n=1 To 20
	Print n, BCD(n),Hex$(BCD(n))
Next

	Function BCD(x As integer) As integer
		BCD=val("&h"+Str$(x))
	End Function

There are no checks that the number you pass will fit, use your skill and judgement