W25Q32 — 32-Mbit (4MB) SPI NOR Serial Flash Memory

Overview

The W25Q32 (W25Q32JV / W25Q32FV) is a 32-Mbit (4 Megabyte) non-volatile SPI NOR serial flash memory IC manufactured by Winbond Electronics. Available in an 8-pin SOIC package or a 5-pin DIP breakout module, it provides external data storage for embedded microcontrollers without SD card slot overhead.

Supporting Standard SPI, Dual-SPI, and Quad-SPI at clock frequencies up to 104 MHz (transfer rates up to $416\text{ Mbits/sec}$ in Quad-SPI mode), the W25Q32 is widely used for storing web server HTML files, UI graphic assets, firmware binaries (OTA updates), audio samples, and file systems (LittleFS, SPIFFS, FATFS) on ESP32, STM32, RP2040, and Arduino boards.

Quick reference


Operating voltage (`VCC`)	2.7 V to 3.6 V DC (3.3 V nominal)
Capacity	32 Mbits ( $4,194,304\text{ Bytes} / 4\text{ MB}$ )
Interface	Standard SPI, Dual-SPI, Quad-SPI (Mode 0,0 & Mode 3,3)
Max SPI Clock	104 MHz (Dual SPI equivalent 208 MHz, Quad SPI equivalent 416 MHz)
Sector erase size	4 KB uniform sectors ( $1,024\text{ sectors}$ total)
Block erase size	32 KB & 64 KB blocks ( $64\text{ blocks}$ of 64KB)
Page program size	256 bytes per page ( $16,384\text{ pages}$ total)
Endurance & Retention	100,000 erase/program cycles / 20-year data retention
Operating current	$4.0\text{ mA}$ active read / $1.0\ \mu\text{A}$ power-down

Pinout (8-Pin SOIC Package & Module Header)

text

             ┌───┴───┐
         /CS ─┤ 1   8├─ VCC
      DO(IO1)─┤ 2   7├─ /HOLD(IO3)
     /WP(IO2)─┤ 3   6├─ CLK
         GND ─┤ 4   5├─ DI(IO0)
             └───────┘

Pin Label	Name	Type	Description
1	`/CS`	Digital Input	Active-Low SPI Chip Select
2	`DO (IO1)`	Digital Output	SPI Serial Data Output / Dual & Quad I/O Pin 1
3	`/WP (IO2)`	Digital Input	Active-Low Write Protect / Quad I/O Pin 2
4	`GND`	Power	Ground reference (0 V)
5	`DI (IO0)`	Digital Input	SPI Serial Data Input / Dual & Quad I/O Pin 0
6	`CLK`	Digital Input	SPI Serial Clock
7	`/HOLD (IO3)`	Digital Input	Active-Low Pause/Hold / Quad I/O Pin 3
8	`VCC`	Power	Supply power input (+2.7 V to +3.6 V DC)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Supply Voltage	$V_{CC}$	2.7	3.3	3.6	V	DC
Active Read Current	$I_{CC1}$	—	4.0	10.0	mA	$f_{CLK} = 50\text{ MHz}$
Program/Erase Current	$I_{CC3}$	—	15.0	25.0	mA	Page program or sector erase
Power-Down Current	$I_{pd}$	—	1.0	5.0	µA	Deep power-down command (`0xB9`)
Page Program Time	$t_{PP}$	—	0.7	3.0	ms	256 bytes page program
Sector Erase Time (4KB)	$t_{SE}$	—	45	400	ms	4 KB sector erase
Block Erase Time (64KB)	$t_{BE}$	—	150	1000	ms	64 KB block erase

Common SPI Command Instructions

Instruction Name	Opcode (Hex)	Description
Write Enable	`0x06`	Sets the Write Enable Latch (WEL) bit prior to write/erase
Read Status Register-1	`0x05`	Reads `BUSY` flag (Bit 0) and `WEL` flag (Bit 1)
Read Data	`0x03`	Reads continuous data bytes starting at 24-bit address
Page Program	`0x02`	Writes up to 256 bytes into a single page
Sector Erase (4KB)	`0x20`	Erases a 4 KB sector (resets all bits to `0xFF`)
Read JEDEC ID	`0x9F`	Returns Manufacturer ID (`0xEF`) and Memory Type (`0x4016`)

Important

Flash Memory Erase Rule:

In NOR flash memory, programming can only change bits from 1 to 0. Changing bits from 0 back to 1 requires performing a Sector Erase (0x20) or Block Erase, which resets all bytes in that 4 KB sector to 0xFF.

Wiring

W25Q32 Pin	Arduino (via Level Shifter)	ESP32	Notes
`VCC`	3.3V Rail	3.3V	Do not connect to 5V
`GND`	GND	GND	System ground
`/CS`	Digital D10	GPIO 5	SPI Chip Select
`CLK`	Digital D13	GPIO 18	SPI Clock
`DI` (MOSI)	Digital D11	GPIO 23	SPI MOSI
`DO` (MISO)	Digital D12	GPIO 19	SPI MISO
`/WP` & `/HOLD`	3.3V	3.3V	Pull High to disable write protect & hold

Example (Arduino `Adafruit_SPIFlash` Library)

cpp

#include <SPI.h>
#include "Adafruit_SPIFlash.h"

// Hardware SPI with CS on pin 5
Adafruit_FlashTransport_SPI flashTransport(5, SPI);
Adafruit_SPIFlash flash(&flashTransport);

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println("W25Q32 SPI Flash Memory Test");

  if (!flash.begin()) {
    Serial.println("Could not find W25Q32 flash chip! Check SPI wiring.");
    while (1);
  }

  Serial.print("Flash chip JEDEC ID: 0x");
  Serial.println(flash.getJEDECID(), HEX);
  Serial.print("Flash size: ");
  Serial.print(flash.size() / 1024 / 1024);
  Serial.println(" MB");
}

void loop() {
  // Read first 16 bytes of sector 0
  uint8_t buffer[16];
  flash.readBuffer(0, buffer, sizeof(buffer));

  Serial.print("First 16 Bytes: ");
  for (int i = 0; i < 16; i++) {
    Serial.print(buffer[i], HEX); Serial.print(" ");
  }
  Serial.println();

  delay(5000);
}

Common mistakes

Connecting 5V logic directly to SPI pins: The W25Q32 operates strictly at 3.3V logic. Connecting 5V SPI lines directly damages the IC. Use level shifters for 5V microcontrollers.
Writing without erasing first: Attempting to write new data over non-erased flash memory results in corrupted data, as 0 bits cannot be flipped back to 1 without a 4KB Sector Erase.

Notes

Winbond W25Q Series Capacity: W25Q16 (16 Mbit / 2 MB), W25Q32 (32 Mbit / 4 MB), W25Q64 (64 Mbit / 8 MB), W25Q128 (128 Mbit / 16 MB).