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(0xFB), the response is eight bytes, intended to be human readable:

__{FB}______________________________

________{56)45)52)2E)31)2E)34)38}___

In the above example, the version string is "VER.1.48". The chips I've seen all follow this pattern

(with various digits, of course), so my utility checks for each character to be the right type (specific

letters, any digits, etc).

Status

The next command to know is how to check the status of the bootloader. We use this command at

various points to make sure the previous operation completed successfully. The request is a single byte

(0x70), and response is two bytes:

__{70}________________

________{SRD1)SRD2}___

There are only a couple of bits that we care about. Bit 7 of SRD1 is set when the bootloader is ready

for another command. Bit 5 is set when an erase command fails. Bit 4 is set when a program

command fails. Bits 3 and 2 of SRD2 tell you if you've "unlocked" the flash by providing the correct

unlock key:

xxxx 00xx

No key provided yet

xxxx 01xx

Wrong key provided

xxxx 11xx

Correct key provided

Throughout this manual, when we say "check the status" we mean to run this command and check the

status bits that are returned. You can also clear the status bits:

__{50}________________

______________________

You should clear the status before erasing or programming the flash, as the error bits for those are

cumulative.

Ok, now that we know how to talk to the bootloader, we need to start the process of downloading the

new application into the flash. We first have to unlock the chip. Then we erase the flash. Then, for

each page (256 bytes) of memory that needs to be programmed, we download that page then read it

back to verify it.

Address Sizes

A quick note on address sizes... The commands we send to the chip all have 24-bit address parameters.

This is because the protocol was designed for the M16C family, which has a 20-bit address. However,

with the introduction of the R32C, which has a 32-bit address, a new command was added to provide

the upper 8 bits of the address separately. Throughout this manual, where you see a command that

takes a 24-bit address, for the R32C, you prefix it with this sequence (0x48, not 0x4B) to provide the

extra bits:

__{48)MSB}____________

For example, to issue a fictitious command CMD with address 0x12345678, we'd do something like

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