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Renesas Electronics Europe - Knowledgebase

How do I program external flash using SH romless parts?

Latest Updated:03/18/2009


How do I program external flash using SH romless parts ?


The normal way to program blank flash on a PCB which has already been fully populated is to put the CPU (bus master) into a bus release state to allow an ATE test rig to be able to program the flash. SH1/2 do not suppport HW standby so it is necessary to use a different mode to achieve this which can be either SW standby or bus release mode (using BREQ). To put the device into SW standby mode it would be necessary to deselect the flash device and perform promulation. It is necessary to execute a number of intstructions to enter SW standby mode including setting the SSBY, SBYCR and executing a SLEEP instruction. The alternative is to use the BREQ pin to cause the device to relinquish the bus which would deselect all external devices automatically & enable you to access the bus pins using an ATE test rig to allow flash programming.NOTE. SH/704X, 703X & 702X have a BREQ pin, 701x does not.
Suitable Products
SH7144 Series
SH7047 Series
SH7046 Series
SH7040 Series