uM-fpu confusion

Tom J

Hi all... I am having on heck of a time geting a number into the floating point unit.
this works

---

fA = lat1
· fHigh = $4524··· '2628.813
· fLow· = $4D03
· GOSUB Load_Float
· GOSUB Fset

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the problem is that i have the numbers in variables but i cant get it to process them

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lat1_bit(0) = 2628
lat1_bit(1) = 8133
fHigh = lat1_bit(0)
fLow = lat1_bit(1)
GOSUB load_float
GOSUB fset

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I have tried using all the "load_float*" support routines that make sense.
I am looking for a way to convert the variable to the correct hex code or properly process the variable with the load routine.
Thank you
Tom Jaeger

camt

Hi Tom,
I assume the numbers you are trying to convert are from a serial source of some kind, and are the left side and right side of a floating point string. To convert to floating point you need to convert the right side to a fraction, then add it to the left side. Alternatively, the uM-FPU can convert an ASCII string directly. Three examples are provided that should solve your problem. Example 1 is the original method you asked about, Examples 2 and 3 use strings.
-Cam

'

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' Example 1
' If the integer and fraction part of a number are converted by SERIN
' and stored as seperate numbers (as in the original question),
' the device must send a fixed number of digits on the right
' side of the decimal point for this method to work. In other words,
' the device must send trailing zeroes (e.g. 123.5000, 123.0500, 123.0050).
' If the device truncates zeroes (e.g. 123.5, 123.05, 123.005), the SERIN
' format conversion will yield 5 for the right side in all cases,
' since leading zeroes are ignored by SERIN. If the format has 4 digits
' to the right of the decimal point, the following code will convert the
' number and store it in register 1 on the uM-FPU.
'

---

val VAR Word(2)

SERIN 0, 16884, [noparse][[/noparse]DEC val(0), SKIP 1, DEC val(1)] 'read left/right values

fA = 1 'select uM-FPU register 1
fLow = val(1) 'load number from right side to uM-FPU
GOSUB Load_FloatWord 'convert to floating point
GOSUB Fset
fLow = 10000 'load 10000
GOSUB Load_FloatWord 'convert to floating point
GOSUB Fdivide 'divide right side by 10000 to get fraction
fLow = val(0) 'load number from left side to uM-FPU
GOSUB Load_FloatWord 'convert to floating point
GOSUB Fadd 'add to fraction
'...

'

---

' Example 2
' This example reads the string (e.g. 2628.8133) directly from the serial
' port and sends it to the uM-FPU for conversion. It terminates the
' conversion when a comma is read from the serial port. This example
' conserves variable space since no extra variables are required.
'

---

GOSUB Load_SerialString 'load
fA = 1
GOSUB Fset
'...

Load_SerialString:
fOpcode = $F9 'convert ASCII to float
GOSUB Sys_Command
DO
SERIN 0, 16884, [noparse][[/noparse]fChar] 'read character from serial port
IF fChar = "," THEN EXIT 'check for comma terminator
SHIFTOUT FpuData, FpuClock, MSBFIRST, [noparse][[/noparse]fChar] ' send character to FPU
LOOP
SHIFTOUT FpuData, FpuClock, MSBFIRST, [noparse][[/noparse]0] ' send zero terminator
RETURN

'

---

' Example 3
' This example reads the string into RAM, then sends it to the uM-FPU for
' conversion. It requires a 10 character string buffer.
'

---

serStr VAR Byte(10)
cnt VAR Byte

SERIN 0, 16884, [noparse][[/noparse]STR serStr\10\","] 'read string
GOSUB Load_RamString
fA = 1
'...

Load_RamString:
fOpcode = $F9 'convert ASCII to float
GOSUB Sys_Command
FOR cnt = 0 TO 10
IF serStr(cnt) = 0 THEN EXIT 'check for comma terminator
SHIFTOUT FpuData, FpuClock, MSBFIRST, [noparse][[/noparse]serStr(cnt)] ' send character to FPU
NEXT
SHIFTOUT FpuData, FpuClock, MSBFIRST, [noparse][[/noparse]0] ' send zero terminator
RETURN