SPI Flash: don't work high-speed read at 48MHz

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I'm using Microchip SST26VF064B SPI Flash memory with an LPC1768 from LPC.

It works until I change the SPI clock frequency from 24MHz to 48MHz.

I'm using HIGH-SPEED READ command that should work up to 104MHz (the  
power supply is 3.3V).

For example I read 0x28 0x26 when they should be 0x51 0x4C.

0010 1000 0010 0110    -> 0x28 0x26
0101 0001 0100 1100    -> 0x51 0x4C

They appears shifted by one bit... except the MSBit of the second byte.

What do you think?

Re: SPI Flash: don't work high-speed read at 48MHz
On 07/03/18 16:51, pozz wrote:
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I'd check the polarity of the clock and the edges used.  There are four  
possible combinations here, and it is not uncommon for one of the wrong  
choices to work at slower speed but fail at higher speed.  Sometimes  
these things are wrong no matter how carefully you follow the  
documentation - it seems to follow the 50%/90% rule (if you have 50%  
chance of guessing correctly, you have 90% chance of guessing incorrectly).


Re: SPI Flash: don't work high-speed read at 48MHz
On 03/07/2018 10:51 AM, pozz wrote:
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Sure you're reading on the right clock edge?

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
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Re: SPI Flash: don't work high-speed read at 48MHz
Il 07/03/2018 16:51, pozz ha scritto:
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It seems SSP peripheral of LPC1768 MCUs (the peripheral I'm using) has  
an upper limit of 33MBit/s. I see this limit in the datasheet.


Re: SPI Flash: don't work high-speed read at 48MHz
On 03/08/2018 03:10 AM, pozz wrote:
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So switch to the wrong clock edge. ;)

Cheers

Phil Hobbs


--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.

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