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IR Thermometer interfacing Problem ..

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th3gr8

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Hello everybody ..
I am working on interfacing of IR Thermometer with PIC 16f877a .. The thermometer has 24c04 eeprom and my task is to fetch data from this eeprom chip .. I used below circuit for level shifting (but used 2n7000) .. I am using PIC CCS and My coding is:
‪
Code: 
#‎include‬ <16F877A.h>
‪#‎fuses‬ xt, nowdt, nolvp, brownout
‪#‎use‬ delay (clock = 4Mhz)
#use rs232(baud=9600, xmit=PIN_B0, rcv=PIN_B1)
#include <2404.c>

void main()
{
unsigned char i,data;
init_ext_eeprom();
delay_ms(20);
while(1)
{
if(!input(PIN_A0))
{
for(i=1;i<=200;i++)
{
data = read_ext_eeprom(0x00+i-1);
delay_ms(10);
printf("%c %d\n\r", data,data);
}
}
}
}

But i dont get any character value at hyperTerminal (and only get 0 as integer) :( .. Please help !! .. i2c-level-shift-mosfet.pngi2c.jpg
 

But i dont get any character value at hyperTerminal (and only get 0 as integer)
Click to expand...
Are you simulating this circuit in a simulator...or are you making this using a development board.?
 

The code you posted above is not explicitly related to some IR Thermometer reading, and performs the task supposed to do: Just a sequential scan on EEPROM content. Can you assure the memory is not entirely cleaned ?



+++
 

udayan92 said:
Are you simulating this circuit in a simulator...or are you making this using a development board.?
Click to expand...

I am implementing it on hardware ..

- - - Updated - - -

andre_teprom said:
The code you posted above is not explicitly related to some IR Thermometer reading, and performs the task supposed to do: Just a sequential scan on EEPROM content. Can you assure the memory is not entirely cleaned ?




+++
Click to expand...

My IR Thermometer is the gadget i bought from the market .. Thermometer manual says that it stores 30 readings and this EEPROM is the only storage i can see on its PCB, so it has to store data in the EEPROM chip .. How can i make sure that memory is not cleaned??
 


If the other kit is able to write on device, if both boards employs compatible firmware driver for writing on these EEPROMs, and if you can interchange both memories, really don´t need an external reader, at least for while. However such test would just validate the code above, which just performs solely the reading task.



+++
 

andre_teprom said:
If the other kit is able to write on device, if both boards employs compatible firmware driver for writing on these EEPROMs, and if you can interchange both memories, really don´t need an external reader, at least for while. However such test would just validate the code above, which just performs solely the reading task.



+++
Click to expand...

These compatibility issue may cause a problem to me :( .. I dont think such EEPROM readers are available here, do you have any tested circuit of the reader??
 

th3gr8 said:
I dont think such EEPROM readers are available here, do you have any tested circuit of the reader??
Click to expand...

I´ve designed many years ago a small circuit able to read a 25Cxx SPI based EEPROM, but PC interface was based on obsolete DB-25 parallel port, so that I´m not sure if this could be useful for you. By the way, follows a snapshot of the design:

EEPROM_SCH.PNG

EEPROM_PCB.PNG



+++
 

Thanks .. Any reader circuit for 24cXX ??
 

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