In SX Microcontrollers, SX/B Compiler and SX-Key Tool, inaki wrote:

I am testing a FM25640 Ramtron chip (8KB).
For testing purposes I am holding high, hardwired, pins HOLD and WP.

I am only managing the pins CS, SO, SI and SCLK.

I am using port C, pins 0 to 3.

 

The problem is that I cannot read back the data I am writing. I always get zero when reading.

 

Is it right to have the pins HOLD and WP high all the time ? :confused:  

 

This is how I write and read one byte:

 

Enable CS (that is, put it to zero)

Shiftout of the command Write Enable (6) (MSB first)

Disable CS (put it to one)

Enable CS

Shiftout of the command Write (2)

Shiftout of zero (address high byte)


Shiftout of zero (address low byte)

Shifout of data $5A

Disable CS

Enable CS

Shiftout of command Read (3)


Shiftout of zero (address high byte)


Shiftout of zero (address low byte)

ShiftIN of data to be read

Disable CS

 

It is supposed I should read $5A but I read $00.

 

Do you see anything wrong with this scheme ?

 

To be honest I am starting to wonder if the Ramtron chip is working at all !

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