Chapter 9: Using User Flash Memory in MAX II Devices
9–27
Software Support for UFM Block
1. nCSis pulled low to indicate the start of transmission.
2. An 8-bit READopcode (00000011) is received from the master device. (If internal
programming is in progress, READis 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 READoperation. When the end of the UFM storage array is reached, the
address counter rolls over to the start of the UFM to continue the READoperation.
5. nCS is pulled back to high to indicate the end of transmission.
For SPI Base mode, the READoperation is always performed through the following
sequence in SPI:
1. nCSis pulled low to indicate the start of transmission.
2. An 8-bit READopcode (00000011) is received from the master device, followed by
an 8-bit address. If internal programming is in progress, the READoperation is
ignored and not accepted.
3. Data is transmitted for as many words as needed by the slave device through SO
for READoperation. 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 SOport.
4. nCSis pulled back to high to indicate the end of transmission.
Figure 9–26. READ Operation Sequence for Extended Mode
nCS
SCK
0
1
2
3
4
5
6
7
8
9
10 11
20 21 22 23 24 25 26 27
36 37 38 39
8-bit
Instruction
16-bit
Address
SI
03H
MSB
MSB
High Impendance
SO
16-bit Data Out 1
16-bit Data Out 2
MSB
MSB
© October 2008 Altera Corporation
MAX II Device Handbook
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