====== Pmod SF3 Reference Manual ======
The Digilent Pmod SF3 (Revision A) provides 32 MB of serial Flash memory.

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== Download This Reference Manual ==
  * {{ :reference:pmod:pmodsf3:pmodsf3_rm.pdf | }}

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===== Features =====
  * 32 MB serial NOR Flash memory
  * Supports extended SPI protocol, dual I/O, and quad I/O
  * Minimum 100,000 erase cycles per sector
  * More than 20 years data retention
  * 12-pin Pmod connector with SPI interface
  * Follows Digilent Interface Specification Type 2A

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=====Functional Description =====
The %%Pmod SF3%% utilizes Micron's NOR Flash memory (N25Q256A) to provide easily accessed non-volatile memory to system boards. The data sheet can be found [[https://www.micron.com/parts/nor-flash/serial-nor-flash/n25q256a13esf40g?pc=%7B8211C822-468A-4C3B-A530-ECB074FBE385%7D|here]].

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=====Specifications =====

^  Parameter                                                   ^  Min  ^  Typical¹  ^  Max  ^  Units    ^
| Recommended Operating Voltage                                |  2.7   |  3.3      |  3.6  |  V        |
| Maximum Supply Voltage                                       |  -0.6  |  -        |  4.0  |  V        |
| Power Supply Current²                                        |  -     |  -        |  20   |  mA       |
| Power Supply Standby Current                                 |  -     |  -        |  100  |  µA       |
| SPI Clock Speed³                                             |  -     |  25       |  104  |  MHz      |
| PAGE PROGRAM time (256 bytes)                                |  -     |  0.5      |  5    |  ms       |
| Sector ERASE time                                            |  -     |  0.7      |  3    |  s        |
| Bulk ERASE time                                              |  -     |  240      |  480  |  s        |

Note¹ - Data in the Typical Column uses V<sub>CC</sub> at 3.3V unless otherwise noted \\
Note² - During a read, program, or erase command \\
Note³ - When used with host boards that include series resistors on the Pmod ports the recommended max speed is 25MHz

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===== Interfacing with the Pmod=====
The %%Pmod SF3%% communicates with the host board via the [[pmod:communication_protocols:spi|SPI protocol]]. By bringing the Chip Select line logic level low voltage, users may issue a single byte instruction code to memory chip. A table of available commands can be found in the data sheet for the N25Q256A [[https://www.micron.com/parts/nor-flash/serial-nor-flash/n25q256a13esf40g?pc=%7B8211C822-468A-4C3B-A530-ECB074FBE385%7D|here]] starting on page 28.

The memory is byte-addressed with the range of 0x000000 to 0x1FFFFFF and is organized into 256 byte pages, 4 KB subsectors, and 64 KB sectors. The memory is written by using an Erase-Program cycle. The smallest programmable unit is one page and the smallest erasable unit is 1 subsector.

Users that wish to simply use the memory module without concerning themselves with the dual/quad input and output communication may use the example code and tutorials found on the [[pmod:pmodsf3:start#example_projects|Pmod SF3 Resource Center]]. 

==== Pinout Description Table ====
^  Pin  ^  Signal    ^  Description          |   ^  Pin  ^  Signal   ^  Description                 | 
|  1    |  ~CS       |  Chip Select          |:::|  7    |  NC       |  Not Connected               |
|  2    |  MOSI/DQ0  |  Master-Out-Slave-In  |:::|  8    |  RST      |  Reset                       |
|  3    |  MISO/DQ1  |  Master-In-Slave-Out  |:::|  9    |  W/DQ2    |  Write Protect               |
|  4    |  SCK       |  Serial Clock         |:::|  10   |  HLD/DQ3  |  Hold                        |
|  5    |  GND       |  Power Supply Ground  |:::|  11   |  GND      |  Power Supply Ground         |
|  6    |  VCC       |  Power Supply (3.3V)  |:::|  12   |  VCC      |  Power Supply (3.3V)         |

Any external power applied to the %%Pmod SF3%% must be within 2.31V and 3.7V; it is strongly recommended the Pmod is operated at 3.3V.
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===== Physical Dimensions =====
The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long on the sides parallel to the pins on the pin header and 0.8 inches long on the sides perpendicular to the pin header.
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===== Additional Information =====
The schematics of the %%Pmod SF3%% are available {{reference/pmod/pmodsf3/pmodsf3_sch.pdf|here}}. Additional information about the %%Flash Memory%% module including communication modes and specific timings of the chip can be found by checking out its datasheet [[https://www.micron.com/parts/nor-flash/serial-nor-flash/n25q256a13esf40g?pc=%7B8211C822-468A-4C3B-A530-ECB074FBE385%7D|here]]. 

More specific information about how to use the %%Pmod SF3%% can be found by checking out the [[pmod:pmodsf3:start#example_projects|PmodSF3 Resource Center]]. 

If you have any questions or comments about the %%Pmod SF3%%, feel free to post them under the appropriate section ("Add-on Boards") of the [[https://forum.digilent.com/|Digilent Forum]].