SDI Technologies SDIO Card - Manual (Page 20)

©Copyright 2002-2006 SD Card Association
SDIO Card Bluetooth Type-A Simplified Specification Version 1.00
13
4.3.2 Byte Basis Transfer Mode
This section describes the way of keeping packet boundary and recovering from CRC errors in Byte
Basis transfer mode. See Appendix D for details of data transfer operation.
Figure 8 describes the Type-A Transport packet Write operation from the Host to the Card in Byte Basis
transfer mode. When the Type-A Transport in the Host writes a packet to the Card through the SDIO
Interface, it divides the Type-A Transport packet into several SDIO data packets. Assuming that L
denotes the length of a Type-A Transport packet (in bytes) and B denotes the maximum byte count in
Byte Basis transfer mode (B < L). There are [L / B] SDIO data packets to be sent. The Type-A Transport
in the Host repeatedly sends all SDIO data packets using Byte Basis transfer mode until all the SDIO
data packets are sent. In Figure 8, the maximum transfer size is used in each SDIO data. However,
smaller byte counts may also be used for this purpose.
When a CRC error occurs in an SDIO transmission, the Type-A Transport in the Host recognizes it
through the transmission result and it sets the PCWRT field to "1" in order to prepare for a re-write.
Then it shall try to re-send the whole Type-A Transport data packet, including the erroneous SDIO data
packet, until the erroneous packet is sent successfully or a number of retries designated by the Host are
reached. If the packet is not sent successfully, the Type-A Transport sends a fatal error to the Host
application. The Host application should reset the Type-A Transport to resume Bluetooth
communication.
Figure 8 – Type-A Transport Packet Write Operation from the Host to the Card in Byte
Basis Transfer Mode
Length (3 Bytes) Interface data (L-4 Bytes)
Data (B Bytes)
SDIO
Protocol
Multiplexing
Adaptation
Type-A Transport
SDIO Data (B Bytes) SDIO Data (B Bytes) SDIO Data (B Bytes)
Byte Basis mode Byte Basis mode Byte Basis mode
When CRC error occurs in transmission, the Type-A Transport packet is re-sent
SDIO Data
(L mod B Bytes)
Service ID (1 Byte)
Data (B Bytes) Data (B Bytes) Data (L mod B Bytes)
Byte Basis mode