Why function rfalNfcvPollerReadMultipleBlocks return ERR_REQUEST when numOfBlocks = 32?

[Oros Nig]

Hi,

I use a X-NUCLEO-NFC06A1shield and a Nucleo-476RG to read a NFC chips ( M24LR64D-W or M24LR04).

For my test I use the demo program from ST provided with the shield.

I want to read 32 blocks (a block is 4 bytes) with the function rfalNfcvPollerReadMultipleBlocks.

If the numOfBlocks parameter is set to 31 the function works correctly.

If the numOfBlocks parameter is set to 32 the function returns ERR_REQUEST.

Could you help me to resolve this issue?

Thx & Regards

Nigoros

Note 1: The chip M24LR04 is on a red board M24LR-discovery.

Note 2: To read the chip M24LR64D-W I use the function rfalST25xVPollerM24LRReadMultipleBlocks with the same issue.

[Brian TIDAL · Accepted solution]

Hi,

the M24LR04 supports a maximum of 32 blocks in one Read Multiple Blocks command (see M24LR04E-R Datasheet §26.5 "The maximum number of blocks is fixed at 32 assuming that they are all located in the same sector"). The number block is encoded in numOfBlocks  minus 1 i.e. a value of '06' in the "Number of blocks" field requests to read 7 blocks. A value of '00' requests to read a single block. 

When setting numOfBlocks to 32, this actually requests 33 blocks and the tag returns an error.

Using numOfBlocks = 31 will return 32 blocks

Rgds

BT

[Oros Nig]

Super!

I take into account your response and now it works.

The header of the function is not very verbose about it.

Thx & regards

[Brian TIDAL]

Hi,

Actually, numOfBlock is the number of blocks to read in addition to the one specified by firstBlockNum. This numOfBlocks parameter follows ISO/IE 15693-3 encoding of "number of blocks" in read Multiple Blocks command.

I will anyhow report your feedback to the developers.

Rgds

BT