RM0082
BS_Serial memory interface
Doc ID 018672 Rev 1
311/844
15.8.6 SMI_TR
register
The SMI_TR is the transmit register which is used by SMI to send either data or commands
to external serial memory. In particular, SMI_TR is a 8 bit barrel shifter, where byte0 is sent
first and then 8 bits are shifted before sending byte1 and so on. The SMI_TR bit
assignments are given in
.
This register can be written in software mode only (bit SW set in SMI_CR1 register,
), and when actual transfer is not yet started (bit SEND cleared in SMI_CR2
register,
).
Note:
The SMI_TR is also used in hardware mode, but its content is not kept entering in this
mode.
15.8.7 SMI_RR
register
The SMI_RR is the receive register which is used by SMI to receive data from external serial
memory. Received bytes from external memory are first placed in byte0, then in other next
fields of SMI_RR until byte3. The SMI_RR bit assignments are given in
[08]
TFF
1’h0
RO
Transfer finished flag.
This bit is set when transfer with external memory is
completed, that is after REC_LENGTH and TRA_LENGTH
bytes (set in SMI_CR2 register,
) have been
received and transmitted, respectively. Besides, TFF is set
when either the read status register (bit RSR in SMI_CR2)
or the write enable (bit WEN in SMI_CR2) commands are
finished.
[07:00]
SMSR
8’h0
RO
Memory device status register.
This 8 bit field is used to store a copy of the external
memory status register. This field is updated in 2 distinct
ways: at first, when the RSR bit in SMI_CR2 register is set
(SMSR is updated after the RSR sequence), and after a
write request to a memory bank (SMSR is updated until the
write cycle is finished, that is when bit [0] of this field is
cleared).
Note: This field is refreshed every 8 SMI_CLK periods.
Table 243.
SMI_SR register bit assignments (continued)
Bit
Name
Reset
value
Type
Description
Table 244.
SMI_TR register bit assignments
Bit
Name
Reset value
Description
[31:24]
Byte3
8’h00
Transmit register (8 bit barrel shifter).
[23:16]
Byte2
8’h00
[15:08]
Byte1
8’h00
[07:00]
Byte0
8’h00