Dewpointer Опции

[Andrejka]

Hi, I found a schematic of simple temperature, huminidity and dewpoint measuring cicruit. Originally device uses: Sht11 sensor, AT90S8535 MCU, and HD44780 like 20x4 LCD. In my project I replace Sht11 with Sht15 (from Sparkfun), At90s8535 is replaced with newer Atmega8535 (Atmel datasheets say - this is a at90s8535 direct repalcement). But this device working incorrectly, so I have only "Sht11 Monitor" label on LCD, without sensor readings. If possible please help me with source code.

Source project:







URL:
Source project - http://www.embedtronics.com/sht11/sht11.html
Source code - http://www.embedtronics.com/sht11/shtdemo1.c
Schematic - http://www.embedtronics.com/sht11/SHT11Sch.pdf


My device show only this label:



I tried to simulate device in Proteus simulator but this program show the same screen, without sensor readings, only label.


Thank You!

[Andrejka]

My Atmega8535 fuses are: CKSEL3..0 - 1111, and I using exeternal 4 MHz crystal, the same as in original design from http://www.embedtronics.com/sht11/sht11.html

Sht11 and Sht15 sensors manufacturer provide a sample C code for AT89S53 with data output into UART (for eg. PC hyperterminal).

http://www.sensirion.com/en/pdf/product_in...ensor_SHTxx.pdf

Сообщение отредактировал Andrejka - Jan 5 2009, 14:44

[korobov_michael]

Sample_Code_humidity_sensor_SHTxx.pdf

I have modeled the design in Proteus. Due to differences in architectures 8051 and AVR there are time restrictions in C instructions. Each assembler instruction in 8051 requires 12 clock cycles and in AVR it takes approx two cycles. So the same code will take different cycles to complete. At first time I obtained errors during measurement. When I inserted delays in code

Код

for (i=0;i<65535;i++)
   {
        __delay_cycles(14); //approx. 1us at 14.7456MHz quartz
        if(PINB&_BV(0) == 0)
            break; //wait until sensor has finished the measurement
   }

in function s_measure(), I obtained all measurements are adequate.

P.S. I'm using IAR, so you have to use your delay function. If you want, I'll give you source codes for IAR that I have made to test.
Regards!

Сообщение отредактировал korobov_michael - Jan 5 2009, 20:08

[_Pasha]

Each assembler instruction in 8051 requires 12 clock cycles and in AVR it takes approx two cycles.

You simply made this timeout long enough.

2Andrejka: what about watchdog? Is it kept off?