Datasheet

40.8.5 Transfer Mode Register
Name: TMR
Offset: 0x0C
Reset: 0x0000
Property: -
This register is used to control data transfers. The user shall set this register before issuing a command
which transfers data (refer to bit DPSEL in CR), or before issuing a Resume command. The user must
save the value of this register when the data transfer is suspended (as a result of a Suspend command)
and restore it before issuing a Resume command. To prevent data loss, this register cannot be written
while data transactions are in progress. Writes to this register are ignored when bit PSR.CMDINHD is '1'.
Table 40-1. Determining the Transfer Type
MSBSEL BCEN BCR.BLKCNT Function
0 Don’t care Don’t care Single Transfer
1 0 Don’t care Infinite Transfer
1 1 Not Zero Multiple Transfer
1 1 Zero Stop Multiple Transfer
Bit 15 14 13 12 11 10 9 8
Access
Reset
Bit 7 6 5 4 3 2 1 0
MSBSEL DTDSEL ACMDEN[1:0] BCEN DMAEN
Access
R/W R/W R/W R/W R/W R/W
Reset 0 0 0 0 0 0
Bit 5 – MSBSEL Multi/Single Block Selection
Write this bit to '1' when issuing multiple-block transfer commands using DAT line(s). For any other
commands, write this bit to 0. If this bit is 0, it is not necessary to write BCR to '1' (refer to Table 1-4).
Bit 4 – DTDSEL Data Transfer Direction Selection
This bit defines the direction of the DAT lines data transfers. Write this bit to '1' to transfer data from the
device (SD Card/SDIO/e.MMC) to the peripheral. Write this bit to '0' for all other commands.
Value Name Description
0
WRITE Writes data from the peripheral to the device.
1
READ Reads data from the device to the peripheral.
Bits 3:2 – ACMDEN[1:0] Auto Command Enable
Two methods can be used to stop Multiple-block read and write operation:
1. Auto CMD12: when the ACMDEN field is set to 1, the peripheral issues CMD12 automatically when
the last block transfer is completed. An Auto CMD12 error is indicated to ACESR. Auto CMD12 is
not enabled if the command does not require CMD12.
SAM D5x/E5x Family Data Sheet
SD/MMC Host Controller ...
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1323