Hello Guys, i need help porting a function to c for my Mega32. Could anybody please help me with the following ?I tried several Times but failed all the time :-( pullup = 220 'not as static value, might change adc = 500 'will be read from mega later B = 3963 'Bwert NTC Ts = 333.15 'Bezugstemperatur in Kelvin 60°C rs = 221 'Widerstand bei Bezugstemperatur TS temp = ((b * Ts) / ((Ts * (Log(((((0.0047898 * adc) * pullup) / (4.9 - (0.0047898 * adc))) / rs)))) + b)) - 273.15 Thanks in Advance
1 | #include <avr/io.h> |
2 | #include <math.h> |
3 | |
4 | // Testdata
|
5 | uint16_t pullup = 220; // not as static value, might change |
6 | uint16_t adc = 500; // will be read from mega later |
7 | int16_t B = 3963; // Bwert NTC |
8 | double Ts = 333.15; // Bezugstemperatur in Kelvin 60°C |
9 | uint16_t rs = 221; // Widerstand bei Bezugstemperatur TS |
10 | double temp = 0; |
11 | |
12 | int main(void) |
13 | {
|
14 | temp = ((B * Ts) / ((Ts * (log(((((0.0047898 * adc) * pullup) |
15 | / (4.9 - (0.0047898 * adc))) / rs)))) + B)) - 273.15; |
16 | asm volatile ("nop"); |
17 | }
|
1) Ergebnis: temp = 61.4 2) log = natürlicher Logarithmus http://www.nongnu.org/avr-libc/user-manual/group__avr__math.html#ga7f7d556ab6b6235777a179647c152126 3) Projektoptionen in AVR-Studio: libm.a hinzufügen
I worked on the function a bit but it didnt work yet, what i did uint32_t temp; // b = 3963 'Bwert vom NTC // Ts = 333.15 'Bezugstemperatur in Kelvin hier 60°C // rs = 221 'Widerstand bei Bezugstemperatur TS analog = adcwert(i); temp =((3963 * 333.15) / ((333.15 * (log(((((0.0047898 * analog) * 1242) / (4.9 - (0.0047898 * analog))) / 221)))) + 3963)) - 273.15; sendUSART(temp); but i get the wrong data, mhh
Danke,wunderbar das deckt sich fein mit meinen 61,39 libm.a hab ich drin, aner wenn ich das nun über usart schicken möchte meckert der compiler rum sendUSART(temp); ../measure.c:158: error: incompatible type for argument 1 of 'sendUSART' muss ich das vorher noch wandeln ?
Yes. The dtostrf() function converts the double value passed in val into an ASCII representationthat will be stored under s. The caller is responsible for providing sufficient storage in s. http://www.nongnu.org/avr-libc/user-manual/group__avr__stdlib.html#ga060c998e77fb5fc0d3168b3ce8771d42
Works like a Charm now, just one Problem i still have is that i need the
resulting value temp converted to single hex values.
Meaning if a Temperature result would be 12.9 i want to have a result of
seg0 = 1
seg1 = 2
seg2 = 9
i tried with
dtostrf(temp,3,1,ascii);sendUSART(ascii); sendUSART("\r\n");
if ( temp > 10 )
{
strncpy(seg0, ascii , 1);
strncpy(seg1, ascii +1, 1);
strncpy(seg2, ascii +3, 1);
}
but since this still results the ascii values
(seg0 ="1",seg1 ="2" and seg2 ="9")
, how do i convert them to hex codes ?
Thanks in Advance
Tried that before already, but i stll need to convert the Value since the Compiler gives me error: lvalue required as increment operand Since i needed to define my seg0 to seg9 values as char i cant add '0'
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