simple write and read location in eemem plug

Jee Labs Talk » How can I fix ... ?

simple write and read location in eemem plug

(4 posts) (2 voices)

Tags:

No tags yet.

joop
I just want to write and read a location in de eemem plug ,
but I get the value 0xFF back, location 0x2000 value 0x55.

void loop() {
delay(1000);
// value to address 0x2000
eemem.send();
eemem.write(0x20);
eemem.write(0x00);
eemem.write(0x55);
eemem.stop();

// read address 0x2000
eemem.send();
eemem.write(0x20);
eemem.write(0x00);
eemem.receive();
byte value = eemem.read(1); ( I don't understand this ,what does the value 1)

eemem.stop();
```
        Serial.println(value,HEX); output is 0xFF mustbe 0x55
```
Posted 12/11/2009 13:28:25
jcw

The "1" in the read() is part of the I2C protocol, it signals that this is the last byte read request and that a stop condition will be set when done.

It think that 0xFF also gets returned when the chip is not responding. To make sure that a slave is responding, check the return value of the send() call, it should be non-zero.

Posted 12/11/2009 21:38:37
joop

eemem.pde worked ok. so ,then the chip was responding. I'll try to check the
return value.

Posted 13/11/2009 07:42:21

joop

it seems it needs a delay between read and write operations = delay(5).

here is the new code

void loop() {
delay(1000);
// write value to address 0x2000
eemem.send();
eemem.write(0x20);
eemem.write(0x00);
eemem.write(0x55);
eemem.stop();
--> delay(5);

        // read address 0x2000

	eemem.send();

	eemem.write(0x20);

	eemem.write(0x00);

	eemem.receive();

	byte value = eemem.read(1);
        eemem.stop();

        Serial.println(value,HEX);
value is now ofcourse 0x55.

chip used is 24m01rp ST K915a

Posted 13/11/2009 08:51:34