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Dedericus
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Joined: 19/01/2018
Location: United Kingdom
Posts: 4

Posted: 02:38pm 13 Mar 2019

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Hi
I am using a Maximite to communicate with a SPI EEPROM 25LC512. To write a byte of data requires 4 bytes:- the cmd byte, address high, low and then the data byte.
To read data requires three bytes: the cmd byte, address high, low. The data at the address is then clocked back but I don�t know how to get a hold of this data.
My code is:

PIN(17)=1 'preset pin17 before it is setup
Setpin 17, DOUT
SPI OPEN 4000000,0,8 '4MHz, Mode 0,8 bits
PIN(17)=0 'chip select low
SPI WRITE 4,2,0,5,8 'write 4 bytes, '2'is write instruction,
' 0005' is the memory location, 8 is data
PIN(17)=1 'CS high
'try to read back
Pause(100)
PIN(17)=0 'CS low
SPI Write 3,3,0,5 'Send the read command to the EEPROM
' Read 3 bytes,the next'3' is read cmd, 0005 is memory location
byte1=SPI(0) 'Trying to get byte from memory
PIN(17)=1
SPI CLOSE

?byte1

Any suggestions to sort the code would be welcomed.
Thanks

WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2959

Posted: 06:18pm 13 Mar 2019

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Replace:

byte1=SPI(0)

with:

SPI READ 1,byte1 'read one byte into variable: byte1

Let us know if this works for you!!

EDIT 1:

If the above works, then move on to:

SPI READ n,ww() 'read n bytes into array ww (rename as appropriate!!)

EDIT 2:

Refer to Page 93 (bottom) and Page 94 in User Manual - explained in a little more detail there.

Hope this helps.Edited by WhiteWizzard 2019-03-15

Dedericus
Newbie

Joined: 19/01/2018
Location: United Kingdom
Posts: 4

Posted: 08:21pm 13 Mar 2019

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Hi

Thanks for the reply.
I tried your suggestion of SPI READ 1,byte1 but the response when run was 'cannot find byte1'.
I am reasonably confident that my hardware is ok butI'll keep looking.

WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2959

Posted: 08:27pm 13 Mar 2019

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Dim ww() ��add to start of code

Then change your spi write to:
ww()= SPI WRITE 3,3,.......

Then add:
Print ww(0)
Print ww(1)
Print ww(2)

Etc

Dedericus
Newbie

Joined: 19/01/2018
Location: United Kingdom
Posts: 4

Posted: 04:54pm 14 Mar 2019

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Thanks for the suggestions.
I tried what you suggested but no success. I then modified my code to be similar to that on page 95 of the manual - still no success.:

OPTION Base 1

DIM ww%(4)
PIN(17)=1 'preset pin17 before it is setup
Setpin 17, DOUT
SPI OPEN 500000,0,8 '500 kHz, Mode 0,8 bits
PIN(17)=0 'chip select low
SPI WRITE 7,2,0,5,8,7,6,5 'write 4 bytes, '2'is write instruction,
' 0005' is the memory location, 8,7,6,5 is data
PIN(17)=1 'CS high
'try to read back
Pause(100)
PIN(17)=0 'CS low
SPI Write 3,3,0,5 'Send the read command to the EEPROM
' Read 3 bytes,the next'3' is read cmd, 0005 is memory location
SPI READ 4,ww%() 'read 4 bytes starting at 0005.
PIN(17)=1
SPI CLOSE

Print ww%(1)
Print ww%(2)
Print ww%(3)
Print ww%(4)

The program when run gives 255 for each location. This suggests the EEPROM is not being written to.
I checked with my scope that there were clk pulses from the uP - that was ok but I did not see any pulses on the SPI data in pin.
I am stepping back from this for a couple of days and come back to it with a clear head.
Thanks for your suggestions.

WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2959

Posted: 05:05pm 14 Mar 2019

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Hi Derek,

If I get time later tonight I will run your code and drop on a Logic Analyser to monitor the SPI out.

Will also check the data sheet for the 25LC512.

I have gotten this family of SPI memory to work before so hopefully not too much effort . . .

Should have something for you in a couple of days if nobody else chimes in.

WW

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