Problem with Temp reading on DS1631 18F MikroC

[paulfjujo]

hello,



Problem with Temp reading on DS1631 .


The first time i read the TH and TL value, i get 15.00°C and 10.00°C wich are the factory setting.
i can modifiy and read back the 2 theshold value TH and TL of thermostat
with 12 bits of resolution ... No problemo
But when i read Temper , i get a value 10°C above the normal
>30°C for Tamb around 20°C
if i use MSB=0x19 and LSB=0x10 as a Temp value to test the calculation
i get the good value of 25.0625 °C .


MikroC pro 6.50
PIC18F26K22
FOSC=Q=10Mhz, but tests also with internal FOSC at 16Mhz and 1Mhz
Pull up resistor for SDA,SCL tests with 4,7K ( and 2,7K)
IC2 at 100Khz
All test in real world .. (no simulation)


R0=1 R1=1 so 12bits resoluton mode,
1shot=0 so contineous conversions
external Power supply 5,0V
tested also with Pickit2 power up via VDD .. same problem


Even with 9 bits config, i get temp= 30°C for 20°C ambiant
I tested another device ..same bad result .


Some idea ?

View attachment 18F26K22_DS1631.zip

 

[paulfjujo]

if i modify the High level threshold thermostat over the temp value
ie : TH=40.00°C i get a normal reading of temper around T°ambiant value and keep a stable measure +- 0,0625
if i modify agian the TH to 19°C (lower than Tamb)
Temp measure goes from Tamb to > 38°C whis in any secondes.. like an auto over heating !
nota:
The TOut Thermostat ( Led + 6,2K to +5V) never change when
measure Temp change or if i modify the thermostat treshold TH or TL .

same probleme on 2 devices !
i have a big doubt about software , because probability of 2 bad devices is very low.(but not impossible!)

Does someone allready uses thermostat thresholds and encounter this kind of problem..

Can someone test my component with another hardware +Software
i can send it by postal invoice.

link to my application

 

[ud23]

Hi i did not understand your exact problem but i guess its related to about thermo stat function with DS1631

I think its explain it here at below link very good.hope it might help.

https://www.bogdi.ro/electronics/digital clock with date and thermometer/

 

[milan.rajik]

Have you checked this ?

https://www.maximintegrated.com/en/app-notes/index.mvp/id/135

 

[paulfjujo]

Have you checked this ?

https://www.maximintegrated.com/en/app-notes/index.mvp/id/135

Yes, i read all documents, datasheets, application notes about DS1631,
and i am a bit confident with my code, because i folow the datasheet..
and i am also familiar with DS1621 and 1624 , but not same algorithm for Temp measure.

DS1631 Temper Measure gives good result , but ONLY if TH is over now Temp measure..
It is ABNORMAL ..
Factory setting for TH and TL are 15,00 and 10,00 ..less that classic Home ambiant temp (19 to 20°C).
I didn't see any example whis change of the thresholds thermostat values and see the result on "TOut" DS1631 pin.
Reading or writing TH & TL values are OK...

i send an email to Maxim support ...
wait and see there advise.

nota: My devices DS1631 have no Trade mark on it !
i am not sure if they are comming from MAxim or Dallas ...or RPC copy !