7–26
Chapter 7: User Flash Memory in MAX V Devices
Software Support for UFM Block
READ
READis the instruction for data transmission, where the data is read from the UFM
block. When data transfer is taking place, the MSB is always the first bit to be
transmitted or received. The data output stream is continuous through all addresses
until it is terminated by a low-to-high transition at the nCSport. The READoperation is
always performed through the following sequence in SPI, as shown in Figure 7–21:
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. Because 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. nCSis 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 because the UFM sector 0 is
used). The address counter will not roll over when address 255 is reached. The SO
output is set to high-impedance (Z) when all eight data bits from address 255 have
been shifted out through the SOport.
4. nCSis pulled back to high to indicate the end of transmission.
Figure 7–21. 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
SI
8-bit
Instruction
16-bit
Address
03H
MSB
MSB
High Impedance
SO
16-bit Data Out 1
16-bit Data Out 2
MSB
MSB
MAX V Device Handbook
January 2011 Altera Corporation
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