2.8. Flash Read Operations

From the end-user perspective, most operations on the flash device involve writing data. However, there are some circumstances where the flash programmer internally needs to read the contents of flash. When the user requests a write and the data does not entirely fill a block, then optionally, the flash programmer fills the remainder of the block with the existing contents of flash, and this requires reading the block contents prior to erasing and writing it. Reading the contents of flash is also required after writing data to flash, when the user has requested a verify operation and where the flash algorithm does not implement a verify method.

NOR flash devices are normally mapped into target memory, so the Eclipse Flash Programmer plug-in can read the contents of flash by directly reading from the corresponding memory addresses. If for some reason it is not possible to read the contents of flash directly from memory, then you must implement the flashReadBlocks() method in your flash algorithm.

For NAND devices you must always implement the flashReadBlocks() method in your flash algorithm. This is because although NAND devices have their control interface mapped into memory, the data itself is not directly accessible without sending commands to the flash state machine.

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