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SPI Performance issues

Started by Sukasa , Jul 16 2015 02:34 AM

Best Answer Chris Walker , 16 July 2015 - 02:37 AM

Hi Sukasa,

What speed is the processor on your board? The SPI clock speed is a "/2, /4, /8, /16, /32" (i.e. /(2^x)) clock speed...so unless you're running at 80MHz or 160MHz you'll get a lower speed than 10mbps. [somewhere between 5mbps and 10mbps).

Each transaction should happen at the speed specified by that device's SPI Config.

Do you have a logic analyzer that you can use to see the wire traffic?

Chris Go to the full post

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3 replies to this topic

#1 Sukasa

Advanced Member

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32 posts

LocationNanaimo, BC

Posted 16 July 2015 - 02:34 AM

I'm working with a project and trying to write data to an LCD. It's rated up to 10Mhz speed and I've tried to set this in my code, however I'm getting far, far slower data transfer rates than I should. Being as the code is rather complex, I'll link the project github page instead of trying to give you a useless look at it.

My question is, what could I look at as a way to improve my SPI transfer performance into the LCD? I use lower-frequency devices on the bus (rated up to 1Mhz), as well as reading from the SD card at several points during the transfer. Could any of this prevent the 10Mhz transfers from running at 10Mhz?

The project code is available at https://github.com/S...Oven-Controller for reference if needed

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#2 Chris Walker

Secret Labs Staff

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7767 posts

LocationNew York, NY

Posted 16 July 2015 - 02:37 AM Best Answer

Hi Sukasa,

What speed is the processor on your board? The SPI clock speed is a "/2, /4, /8, /16, /32" (i.e. /(2^x)) clock speed...so unless you're running at 80MHz or 160MHz you'll get a lower speed than 10mbps. [somewhere between 5mbps and 10mbps).

Each transaction should happen at the speed specified by that device's SPI Config.

Do you have a logic analyzer that you can use to see the wire traffic?

Chris