Forum Discussion
Honored ContributorCyclone 3 spi interface to mcp2515 spi can chip
HI,
I am trying to write a verilog interface. The interface is between the spi Core and a Mcp2515 Can Controller with a SPI inteface.(just the general interface ). I am not sure about the best way of writing this interface, after obtaining the data sheet for both devices. I think I will have to also use a Sopc Component aswell as the verilog code. Are there any examples of this. Can you start me off with this. Thanks Dave.9 Replies
Altera_ForumJust use the SPI component in SOPC/QSys. Very well documented and easy to use.
- Altera_Forum
Thanks Socrates.
I see the Spi component in Sopc. Would you still have to write code to Read/write The Mcp2515 or is that taken care off in the sopc component. The serial control lines so/si and Sck/cs Thanks Dave - Altera_Forum
The component will do the job, You'll only have to tell the component what to do (read or write), select chipselect and assign data buffers to place data.
- Altera_Forum
Hi Socrates,
If you were using verilog could you give me an example of a read to the Mcp 2515, the format reqd. Many Thanks Dave - Altera_Forum
You don't need HDL at all. The component has everything required, use Nios and code in C.
- Altera_Forum
Hi Socrates,
Sorry to bother you again. We had a problem, are interface between the spi core and the mcp2525 was driven\writen in C. But it was though that the interface could be hard coded , and relive the burdon from the system c routines. (Less interupts for the c code) I was asked to look into the possibility of hard coding the interface. Thanks Dave - Altera_Forum
The SPI component documentation mentions that is is possible to combine it with a DMA component to automate long transfers.
If that doesn't suit your needs, you have two options: - Write a custom SOPC master to control the SPI SOPC component, replacing the logic you have in C. - Write a full-custom SOPC SPI component. - Altera_Forum
Hi Rubalho,
- Write a custom SOPC master to control the SPI SOPC component, replacing the logic you have in C. is there a simple way of doin the above,say in verilog. Thanks Dave - Altera_Forum
One thought is to write a small verilog or vhdl module that will drive the SPI lines, and be controlled by a FSM. The data from the Microchip CAN chip would then be placed into data into a small RAM, that would effectively be dual port. Off chip access by an external uC could be done this way, or simply write the logic to interface to SOPC/Qsys.
Fundamentally, if you want to removed the interrupt burden on the processor, doing the design in HDL always seems to be best. -James
