49.7.2 QSPI Mode Register

This register can only be written if bit WPEN is cleared in the QSPI Write Protection Mode Register.

Name: QSPI_MR
Offset: 0x04
Reset: 0x00000000
Property: Read/Write

Bit 3130292827262524 
 DLYCS[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 
Bit 2322212019181716 
 DLYBCT[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 
Bit 15141312111098 
     NBBITS[3:0] 
Access R/WR/WR/WR/W 
Reset 0000 
Bit 76543210 
   CSMODE[1:0]SMRMWDRBTLLBSMM 
Access R/WR/WR/WR/WR/WR/W 
Reset 000000 

Bits 31:24 – DLYCS[7:0] Minimum Inactive QCS Delay

This field defines the minimum delay between the deactivation and the activation of QCS. The DLYCS time guarantees the client minimum deselect time.

If DLYCS written to ‘0’, one peripheral clock period is inserted by default.

Otherwise, the following equation determines the delay:

DLYCS = Minimum inactive × fperipheral clock

Bits 23:16 – DLYBCT[7:0] Delay Between Consecutive Transfers

This field defines the delay between two consecutive transfers with the same peripheral without removing the chip select. The delay is always inserted after each transfer and before removing the chip select if needed.

When DLYBCT is written to ‘0’, no delay between consecutive transfers is inserted and the clock keeps its duty cycle over the character transfers. In Serial Memory mode (SMM = 1), DLYBCT must be written to ‘0’ and no delay is inserted.

Otherwise, the following equation determines the delay:

DLYBCT = (Delay Between Consecutive Transfers × fperipheral clock) / 32

Bits 11:8 – NBBITS[3:0] Number Of Bits Per Transfer

NBBITS is used only when SMM is set to '0'.
ValueNameDescription
0 8_BIT

8 bits for transfer

8 16_BIT

16 bits for transfer

Bits 5:4 – CSMODE[1:0] Chip Select Mode

The CSMODE field determines how the chip select is deasserted

Note: This field is forced to LASTXFER when SMM is written to ‘1’.
ValueNameDescription
0 NOT_RELOADED

The chip select is deasserted if QSPI_TDR.TD has not been reloaded before the end of the current transfer.

1 LASTXFER

The chip select is deasserted when the bit LASTXFER is written to ‘1’ and the character written in QSPI_TDR.TD has been transferred.

2 SYSTEMATICALLY

The chip select is deasserted systematically after each transfer.

Bit 3 – SMRM Serial Memory Register Mode

ValueDescription
0

Serial Memory registers are written via system bus access. See section Instruction Frame Transmission for details.

1

Serial Memory registers are written via peripheral bus (configuration bus) access. See section Instruction Frame Transmission for details.

Bit 2 – WDRBT Wait Data Read Before Transfer

0 (DISABLED): No effect. In SPI mode, a transfer can be initiated whatever the state of the QSPI_RDR is.

1 (ENABLED): In SPI mode, a transfer can start only if the QSPI_RDR is empty, i.e., does not contain any unread data. This mode prevents overrun error in reception.

Bit 1 – LLB Local Loopback Enable

0 (DISABLED): Local loopback path disabled.

1 (ENABLED): Local loopback path enabled.

LLB controls the local loopback on the data serializer for testing in SPI mode only. (MISO is internally connected on MOSI).

Bit 0 – SMM Serial Memory Mode

0 (SPI): The QSPI is in SPI mode.

1 (MEMORY): The QSPI is in Serial Memory mode.