ESP32 Bit Pirate

ESP32-S3 3-Wire Microwire EEPROM reading

Read 93Cxx Microwire EEPROMs with ESP32

ESP32 Bit Pirate turns a compatible ESP32-S3 board into a 3-Wire Microwire EEPROM workbench. Use it to probe 93Cxx chips, choose x8 or x16 organization, dump memory safely and troubleshoot CS, SK, DI and DO wiring.

Start with a 93Cxx dump recipe Flash ESP32 Bit Pirate
3-Wire Microwire EEPROM reading visual with an ESP32 board and 93Cxx EEPROM

Quick 3-Wire EEPROM workflow

Start read-only. Confirm chip model, ORG state and wiring before writing or erasing any EEPROM, and keep a verified dump outside the target device.

  1. 01

    Connect CS, SK, DI, DO, VCC and GND with short wires or a known-good clip.

  2. 02

    Check the ORG pin state so x8 or x16 organization is known before interpreting a dump.

  3. 03

    Start 3WIRE mode and confirm the configured CS, SK, DI and DO pins.

  4. 04

    Open the EEPROM shell, probe the chip and select the matching 93Cxx model.

  5. 05

    Dump the EEPROM, repeat the dump, then compare results before any write or erase workflow.

mode 3wire
config
eeprom

Example CLI flow. See the 3WIRE wiki for exact syntax, EEPROM shell menu entries and firmware-specific options.

3-Wire workflows covered by ESP32 Bit Pirate

Use this overview to choose the right 93Cxx Microwire EEPROM workflow before opening a detailed recipe.

Probe

93Cxx EEPROM probe

Identify the connected Microwire EEPROM, confirm a supported model and avoid interpreting the wrong capacity or organization.

Dump

93Cxx Microwire EEPROM dump

Back up 93C46, 93C56, 93C66, 93C76 or 93C86 memory before any repair, write, erase or board-level experiment.

ORG

x8 and x16 organization checks

Use the ORG pin state to choose the right memory organization before trusting byte order, size or address interpretation.

Write

Controlled EEPROM byte writes

Practice small write tests only after a verified backup and only on replaceable lab parts or devices you are allowed to modify.

Erase

Disposable lab EEPROM erase

Use destructive erase actions only after saving the original contents and confirming the chip is not production-critical.

Troubleshoot

CS, SK, DI and DO wiring checks

Separate swapped data lines, floating ORG, weak clip contact and target-board interference before blaming the EEPROM.

When an ESP32-S3 3-Wire workbench helps

Microwire EEPROMs often appear in old modules, automotive boards, appliances and small configuration memories. A small external workflow helps preserve data before experiments.

Unknown EEPROM

Before assuming SPI flash

Use 3WIRE mode for 93Cxx-style EEPROMs instead of treating the chip like a normal SPI flash or 25X EEPROM.

Repair bench

Before modifying memory

Probe, record the chip marking and ORG state, then make at least two matching dumps before any write or erase operation.

Bring-up

Before trusting a dump

Check CS, SK, DI, DO, ground, supply voltage, clip pressure and whether the target board is still driving the EEPROM.

3-Wire EEPROM hardware reminders

These notes stay short. The detailed command references live in the project documentation and firmware repository.

CS, SK, DI, DO

93Cxx Microwire EEPROMs use chip select, clock, data input and data output lines. DI and DO swaps are a common cause of silent probes.

ORG pin

ORG selects x8 or x16 organization on many chips. A floating or wrongly tied ORG pin can make a valid dump look wrong.

Supply voltage

Use a known-safe 3.3 V or 5 V setup and avoid unsupported levels. Confirm common ground before connecting signal wires.

Target isolation

In-circuit dumps can fail if the original board drives the EEPROM. Remove power or isolate the chip when needed.

Common 3-Wire EEPROM problems

Most failures come from swapped DI/DO, wrong organization, poor clip contact, target-board interference or destructive actions taken before a backup.

Probe finds nothing

Check CS, SK, DI, DO, VCC, GND, clip orientation and whether the chip is a supported 93Cxx Microwire EEPROM.

Dump size looks wrong

Confirm the exact chip model and ORG pin state before assuming the read is corrupt.

All bytes read as FF

Check wiring and target isolation first. A blank chip may also be harder to identify during probe.

Readback differs

Repeat the dump with shorter wires, better clip pressure and stable supply before comparing memory contents.

Write or erase fails

Verify write-enable behavior, organization mode and circuit write protection, and never test destructive actions on production data.

Detailed 3-Wire EEPROM recipes

These pages are the task-level 93Cxx Microwire workflows. This overview keeps the protocol-level guidance here, while each recipe covers setup, commands and troubleshooting in detail.

Useful 3-Wire references

This page is a protocol overview. Use the site index for the full web experience, or GitHub for source code, firmware documentation and the 3WIRE command reference.

Flash ESP32 Bit Pirate

Flash a supported ESP32-S3 board before testing 3-Wire mode from the browser.

Open Web Flasher

Logic Analyzer

Capture CS, SK, DI or DO timing when you need to inspect the physical signal behavior.

Open Logic Analyzer

ESP32 Bit Pirate GitHub

Check firmware source, issues and releases that affect 3-Wire support.

Open GitHub repository

3-Wire EEPROM FAQ

Short answers for common questions before moving into a detailed workflow.

Can ESP32 Bit Pirate dump a 93Cxx Microwire EEPROM?

Yes. ESP32 Bit Pirate can open the 3-Wire EEPROM shell, probe a supported 93Cxx Microwire EEPROM and dump its memory after the chip model and ORG setting are confirmed.

Is 3-Wire Microwire the same as SPI?

No. 3-Wire Microwire EEPROMs use CS, SK, DI and DO lines and require the dedicated 3WIRE mode and EEPROM shell rather than the normal SPI flash workflow.

Should I write or erase a 93Cxx EEPROM before dumping it?

No. Start with a probe, record the chip model and ORG state, then make at least one read-only dump before any write or erase operation on a replaceable lab chip.