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USB Superspeed Peripherals

JaYe_3798301
New Contributor

Hi all,

I am building a USB device which needs to consume as less power as possible.

I was using Fx3s with SPI-Flash to boot the device, and the typical SPI-flash read current is about 10mA, while the F-RAM needs only 10 times less current.

Would it help to reduce the overall power consumption?

As there would be a 8-Mbits F-RAM coming, Is it possible to use it as the booting flash for Fx3S?

Thanks,

Jay

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1 Solution
SrinathS_16
Moderator
Moderator

Hello Jay,

- The Excelon F-RAMs can be used as replacement for the SPI flash devices for booting. Upon looking into the datasheet of the Cypress Excelon F-RAM, the read/write commands are the same as in the case of FX3 supported SPI boot.

- SPI flash devices use the erase command before writing to the memory. But, F-RAMs do not require erasing. The Cypress Control Center issues the command to erase the SPI flash before write operation. The F-RAM ignores the command and hence the write operation will also be successful. In case, you are writing a custom vendor command in your firmware to write to the F-RAM, the erase command coming from the host must be handled without performing any SPI transfer.

Best regards,

Srinath S

View solution in original post

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7 Replies
SrinathS_16
Moderator
Moderator

Hello Jay,

- The Excelon F-RAMs can be used as replacement for the SPI flash devices for booting. Upon looking into the datasheet of the Cypress Excelon F-RAM, the read/write commands are the same as in the case of FX3 supported SPI boot.

- SPI flash devices use the erase command before writing to the memory. But, F-RAMs do not require erasing. The Cypress Control Center issues the command to erase the SPI flash before write operation. The F-RAM ignores the command and hence the write operation will also be successful. In case, you are writing a custom vendor command in your firmware to write to the F-RAM, the erase command coming from the host must be handled without performing any SPI transfer.

Best regards,

Srinath S

View solution in original post

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JaYe_3798301
New Contributor

Hi Srinath,

Thanks for the response.

Base on your experience, would changing from SPI-flash to F-RAM effectively reduce the run-time current?

Jay

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SrinathS_16
Moderator
Moderator

Hello Jay,

The Excelon F-RAMs consume lesser current compared to the SPI flash.

Best regards,

Srinath S

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JaYe_3798301
New Contributor

Hi Srinath,

For FX3/FX3s, is the program copied from the SPI-Flash to RAM in run-time or the ARM core execute the program directly from Flash?

Jay

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SrinathS_16
Moderator
Moderator

Hello Jay,

The program from the flash is copied into the internal RAM before execution.

Best regards,

Srinath S

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JaYe_3798301
New Contributor

Hi Srinath,

Does copying the program from flash to RAM before execution means that it would be unnecessary to use flash size larger than 512K Byte, which is the largest RAM size. If the flash is only for program, and not to be used to store any data.

Thanks a lot for all the help.

Jay

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SrinathS_16
Moderator
Moderator

Hello Jay,

Though the RAM size is 512kB, the code area inside the RAM is even smaller which is around 180kB in the case of 512kB SRAM FX3. So, a flash device that can store this firmware code is sufficient.

Best regards,

Srinath S

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