Hi,

I'm a newbie in this business, so please excuse me if I ask silly question.

I would like to connect the above mentioned SPI controller to a PicoBlaze device. However, there is no RD/WR on the SPI. As I see there is only data in, data out, address, write and select signals.

Can anyone guide me how to solve this matter?

Thanks,

/sza2

I searched for the SPI core that you mention in your message (spiflashcontrol) but I can't find it.

Anyway, the general idea of connecting peripherals to the Picoblaze lies on the addition of extra I/O ports (you can read about tis operation on the Picoblaze's manuals). Through these ports you can control or read any signals you want.

Ok, sorry...I checked the SPI core that you mention. Except the D_in and D_out signals which can be connected directly to the Picoblaze, you have to add extra I/O ports to communicate with all the other control or data signals. If I guess right, the "wr" signal can be connected to the "write_strobe" signal of the Picoblaze.

Hi,

Thanks.

Well, I think I should investigate the matter more deeply. Actually, in a single PicoBlaze read it is impossible to get back the value from the SPI bus at the time of read signal, since it takes at least 8 SPI clock time for the data to be ready. So first it is necessary to initiate a read cycle, and when all serial bits arrived, can I read it from the parallel d_out.

But since I have no big experience with VHDL, it will take some time...

/sza2

Maybe you have to design an extra unit between the Picoblaze and the SPI, which will deserialize the bit stream from the SPI and output an 8-bit parallel bus to the Picoblaze. At least this is the way an RS-232 UART does it.