Chapter 9: Using User Flash Memory in MAX II Devices
Software Support for UFM Block
9–27
1.
nCS
is pulled low to indicate the start of transmission.
2. An 8-bit
READ
opcode (00000011) is received from the master device. (If internal
programming is in progress,
READ
is ignored and not accepted).
3. A 16-bit address is received from the master device. The LSB of the address is
received last. As the UFM block can take only nine bits of address maximum, the
first seven address bits received are discarded.
4. Data is transmitted for as many words as needed by the slave device through
SO
for
READ
operation. When the end of the UFM storage array is reached, the
address counter rolls over to the start of the UFM to continue the
READ
operation.
5. nCS is pulled back to high to indicate the end of transmission.
For SPI Base mode, the
READ
operation is always performed through the following
sequence in SPI:
1.
nCS
is pulled low to indicate the start of transmission.
2. An 8-bit
READ
opcode (00000011) is received from the master device, followed by
an 8-bit address. If internal programming is in progress, the
READ
operation is
ignored and not accepted.
3. Data is transmitted for as many words as needed by the slave device through
SO
for
READ
operation. The internal address pointer automatically increments until
the highest memory address is reached (address 255 only since the UFM sector 0 is
used). The address counter will not roll over once address 255 is reached. The
SO
output is set to high-impedance (Z) once all the eight data bits from address 255
has been shifted out through the
SO
port.
4.
nCS
is pulled back to high to indicate the end of transmission.
Figure 9–26.
READ Operation Sequence for Extended Mode
nCS
0
1
2
3
4
5 6 7
8
9 10 11
20 21 22 23 24 25 26 27
36 37 38 39
SCK
8-bit
Instruction
SI
MSB
03
H
MSB
16-bit
Address
SO
High Impendance
16-bit Data Out 1
MSB
16-bit Data Out 2
MSB
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