Of the file formats a recovery can deliver, the binary is the most portable and the least self-describing. It is a sequence of bytes. It does not say where they came from, how long they should be, or what order they are in. Everything it does not say has to be established some other way and then written down next to the file.

On an RX62T that is entirely workable, because the architecture places its reset vector at the very top of the four-gigabyte address space. The last four bytes of a correct image are an address, and an address is a falsifiable claim. This single property turns the binary from an unverifiable blob into something that can be checked in ten seconds.

The part is R5F562T6BDFF#V3 — RX62T group, one of the two memory classes the group offers, QFP-type package, version code after the hash. The version code affects paperwork rather than silicon, which means the length of the array is decided by the memory class field and not by the suffix.

What a binary omits

Two rows cause most of the trouble. The length is not a declaration, it is an observation: a file that is two kilobytes short looks like a valid file that is two kilobytes shorter. And a gap in the image is silently filled with zeros, which on this architecture is a legal instruction and therefore does not announce itself.

Three ways a binary is wrong without looking wrong

The first is truncation. A read that stopped early, a transfer that dropped its last block, or a buffer that was sized for the smaller memory class produces a file whose end is missing. On this device the missing end contains the vector table, so the file survives a checksum and fails at the first reset.

The second is padding. A tool that sized the output to the larger memory class, or that padded to a round number, produces a file whose first bytes are right and whose tail is zeros. The vector area reads as zero, which is a plausible-looking address — the start of the flash — and will send a rebuilt device into the start of its own code with no initialisation.

The third is a base offset. A binary has no addresses, so the implied base is a convention. If the read started at an offset other than zero, everything is displaced and the vector table lands in the middle of the file rather than at its end. This is the only one of the three that is easy to spot, because the file length no longer matches the expected array size.

The five-second proof

Read the last four bytes as a thirty-two-bit little-endian value and as a thirty-two-bit big-endian value.

One of the two will be an address inside the flash region — a small number, aligned, and well below the option-setting area at the top of the map. The other will be a value in the hundreds of millions, which is not an address any code can execute from. That comparison proves the base, the endianness and the completeness of the file in one step, because truncation moves the vector out of the last four bytes and padding replaces it with zeros.

Do the same with the exception vectors immediately below. On this architecture those entries are handler addresses, tightly clustered, and a block of four or five that all decode to plausible aligned values in the same region is strong evidence that the image is intact and correctly oriented.

When a binary is the right deliverable

A binary is right when the thing that will consume it expects bytes at an address. Production programmers, some bootloader upload paths and most test fixtures work that way.

A binary is wrong as the only deliverable, because it cannot describe itself. The professional pattern is to deliver both: the binary for the tools that want it, and an addressed file for the people who will inspect it, generated from the same read rather than from two separate reads. The pair then proves itself, because converting one to the other is a lossless operation that can be diffed.

There is an exception worth naming. When the customer’s toolchain is old enough that its binary reader assumes a particular base address, a binary delivered alongside a note stating that base is more useful than a modern format the tool cannot open. That is a support decision rather than a technical one, and it is worth asking about before delivery rather than after.

Recording what the file cannot say

Three facts belong in the delivery note for a binary on this part, and none of them can be recovered from the file later.

The base address, stated explicitly, because it is the one thing a binary cannot express.

The endianness of the original design, because a correct set of bytes decodes into two different programs depending on the answer.

The expected length, with the actual length next to it, so that a future reader can tell a truncated file from a complete one without the datasheet.

For the addressed container that solves all three of those problems at once, R5F562T7EDFF heximal covers record formats. For the byte-order question that the binary cannot answer, R5F562T7BDFF code takes it apart. And for a full bundle rather than a single file, R5F562T6DDFF firmware shows what else travels with the image.

FAQ

Can a binary be converted back to addresses? Only with the base address, which has to come from outside the file. With it, conversion is exact.

Does a zero-filled tail mean the read failed? Not necessarily. It can mean the file was padded to the larger memory class. The vector check distinguishes padding from a genuine empty region.

Is a binary smaller than the array ever correct? Yes, when the design’s code does not use the whole flash. What must be stated is the base and the length actually used, not the length the device could hold.

The short version

A binary says nothing, so everything it omits has to be written down: base, byte order, expected length. The reset vector at the top of the map proves the first and the second, and the file size is only evidence when compared against the memory class. Deliver the binary and an addressed file from the same read, and neither can lie about the other.

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