The PIC16F1939 is the 28 KB flagship of the 28/40/44-pin LCD generation: 16384 words of flash, 1024 bytes of SRAM, 256 bytes of EEPROM, thirty-six I/O lines, sixteen capacitive-touch channels, a fourteen-channel 10-bit ADC, three enhanced CCP modules plus two plain CCP, and the ninety-six-pixel LCD driver it carries. It is the member a product line grows into when the 14 KB parts run out of room but the board cannot grow pins. When its code-protect bit is set, our unlock protected PIC16F1939 software service recovers the image from hardware you own.

Thirty-six lines and a display

With thirty-six I/O lines alongside the LCD driver, this die carries products that both show and act: panels that drive valves, relays and indicators while rendering a menu system. The action side is constant-driven – ECCP steering maps, shutdown thresholds, dead-band values – and the display side is a font and menu table. Recovery captures both dimensions and verifies them on the fixture: every steered output exercised against the donor’s recorded behaviour, every menu screen compared segment for segment. That double proof is what separates a controller clone from a bytes-in-a-file exercise. The memory hierarchy holding both arrays is described in the how the MCU memory works guide.

Brown-out configuration decides how a mains product survives a sagging rail, and the family’s selectable trip points are constants the maker chose deliberately. Our fixture replays a controlled sag against clone and donor and records the trip and recovery on both, because a replacement carrying defaults passes steady-state testing and fails the first real dip – usually in front of the customer rather than in front of the bench.

Protection without destruction

Code protect in the configuration words refuses external reads of program flash; data protect seals the EEPROM; write-protect bits can seal regions against self-programming. Every one of those guards falls only if the array is bulk-erased – which destroys the very data being sought – so the erase is excluded from the workflow by design. The working sequence maps the configuration words first, reads everything that answers in its protected state in one pass, checksums per sector, and re-reads until two passes agree. The report states plainly which regions answered and which were sealed, so the owner knows exactly what was recovered and what the manufacturer’s policy withheld. The lawful-access frame for this work is in the unlock microcontroller embedded memory guide.

Grown firmware and its history

Products that land on the 28 KB member usually have a revision history visible in the array: parameter tables that moved, a protocol that gained versions, sometimes an older build still present above the active code. When donors from several production years arrive together, the images are diffed region by region and the lineage reported – which turns fleet maintenance from guesswork into a schedule. Fleet consolidation onto this die from the 14 KB members is common, and the diff between the two images is usually small enough to act on directly. Bounded-scope jobs follow the pattern on the partial microcontroller chip cloning page.

Menu tables deserve explicit capture attention on this die: the 28 KB member carries products with real menu systems, and the table that maps values to screens is as much a deliverable as the code that walks it. Where two firmware vintages coexist in one fleet, the menu tables are diffed line by line, because that is where a vendor’s revisions become visible to users – a renamed item, a moved setting, a limit quietly raised, or a diagnostic hidden.

Duplication and family

Confirmed images are placed into matching 28/40/44-pin blanks with both EEPROM and configuration words restored, then individually read back through the MCU flash EEPROM data cloning pipeline. The 14 KB members are on the PIC16F1936 source code and PIC16F1937 EEPROM pages, and the 28 KB 28-pin sibling on the PIC16F1938 heximal recovery.

Scope

Work is limited to hardware you own or may lawfully service, with the entitlement logged for each job. Send the locked PIC16F1939 and the deliverable is a verified image, the display and steering evidence, and the protection map. The 171x analogue flagship is compared on the PIC16F1718 firmware page.