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The Four Platform Families

ESP32 · NRF52840 · RP2040 · STM32WL

Four families, one firmware. ESP32, nRF52840, RP2040 and STM32WL share the same source code, but each chip brings its own cores, memory, transports and limits. This chapter walks through them one by one: what the chip brings and what it demands in memory and energy. The comparison, the device list and the decision guide are in MeshCore Platforms.

[!NOTE] Source. This page has been verified against the firmware itself: MeshCore v1.16.0 (FIRMWARE_BUILD_DATE "6 Jun 2026"), commit 03b6ef4, 28 July 2026 — platformio.ini, variants/*/platformio.ini (79 directories, 507 build targets), boards/*.json (41 definitions), examples/companion_radio/main.cpp and docs/nrf52_power_management.md. Every count in this chapter was also checked against commit a3a1aa5 (19 July 2026) and is identical there. To reproduce: tools/platform-overview.py.

ESP32 — the versatile workhorse

Four SoCs under one heading

[esp32_base] (platformio.ini lines 57-65) covers four different chips. The 37 variants divide up roughly like this: about 24 use an ESP32-S3, six the classic ESP32, four a C3 and three a C6. Those are also two different processor architectures: Xtensa LX6 in the classic ESP32, Xtensa LX7 in the S3, and RISC-V in the C3 and C6.

The C6 is an edge case. [esp32c6_base] (lines 72-76) extends esp32_base but pulls its platform from a different URL — pioarduino with Arduino-ESP32 3.x. Above it, the repo itself notes that this is experimental and may be less stable than the other platforms (line 73). Three variants, sixteen build targets, and — see the table further down — not a single ready-made device in the web flasher.

What you get for it

ESP32 is the only family with WiFi (17 build targets), the only one with OTA (36 variants load [esp32_ota], lines 67-70) and the only one with ESP-NOW (src/helpers/esp32/ESPNOWRadio.cpp, 32 variants). On top of that 4 to 16 MB of flash, PSRAM on the more expensive boards, and the second best display support after nRF52.

src/helpers/esp32/ is accordingly the fattest helper directory of the four: BLE, WiFi, ESP-NOW, board classes. For comparison: src/helpers/nrf52/ contains only a BLE interface, and src/helpers/rp2040/ does not exist.

The downside

The highest clock speed of the four — 240 MHz — and the highest power draw. For ESP32 the firmware has no built-in power management like nRF52 does. There is an ESP32_CPU_FREQ build flag in platformio.ini (line 64), but it is commented out; lowering the clock is up to you.

nRF52840 — the frugal one

A fork of the Adafruit core

[nrf52_base] (lines 80-95) does not use a stock Arduino core but a fork of its own:

platform_packages =
  framework-arduinoadafruitnrf52 @
    https://github.com/meshcore-dev/Adafruit_nRF52_Arduino#d541301

The reason is in the comment next to it: a patch to the BLE stack that prevents firmware lockups during rapid connect and disconnect cycles (PR #1177 and #1295).

Two of the 34 nRF52 variants are exceptions: variants/heltec_mesh_solar/platformio.ini line 4 and variants/mesh_pocket/platformio.ini line 4 set platform_packages = framework-arduinoadafruitnrf52 without a URL, so the plain Adafruit core, plus an older SoftDevice linker script (nrf52840_s140_v6.ld). Anyone seeing BLE trouble there now knows where to look.

Beyond that: 64 MHz, 230 KB of RAM, 792 to 796 KB of flash for the application, and two filesystems — InternalFS plus an extra volume compiled in through EXTRAFS=1.

Power management: what exists and where it is missing

docs/nrf52_power_management.md (217 lines) describes what is possible: waking on LPCOMP or VBUS, SYSTEMOFF, and recording the reason for a shutdown. This is the only platform where the firmware genuinely does something about power.

But read the Supported Boards table (lines 38-57) alongside it: of the nineteen boards listed, five are marked "Implemented" — XIAO nRF52840, RAK4631, Heltec T114, GAT562 Mesh Watch13 and SenseCAP Solar. The other fourteen are marked "No", including popular choices such as the T-Echo, T1000-E, Nano G2 Ultra, ProMicro, Mesh Pocket and the ThinkNode M1/M3/M6.

"nRF52 is the frugal family" holds at chip level. Whether your particular board actually benefits is in that table.

The most BLE targets of all

Forty of the 199 nRF52 build targets are a BLE companion. That is two more than the entire ESP32 family, which has three times as many targets.

RP2040 — the simple one

USB serial only

Four variants, 22 build targets, not one with BLE or WiFi. The branches are there, but commented out (examples/companion_radio/main.cpp lines 55-66), and all four variants set lib_ignore = BLE. That includes the Pico W, which does have the hardware for it.

What remains: repeater, room server, KISS modem, terminal chat and a companion over USB. Not a single variant has a display, and there is no src/helpers/rp2040/ directory.

The four boards use PlatformIO's built-in definitions rather than their own boards/*.json. That is why the RP2040 figures in table 1 carry an asterisk.

STM32WL — the integrated one

The radio is on the die

All four STM32WL variants set SPI_INTERFACES_COUNT=0 and RADIO_CLASS=CustomSTM32WLx, and [stm32_base] loads the SubGhz library from the STM32duino core (platformio.ini lines 115, 120). There is no separate SX126x and no SPI bus to the radio: the LoRa transceiver sits on the same die as the processor. How that library is pulled in and what MeshCore does with it is described in SubGhz.

Two block diagrams side by side. On the left an MCU with six SPI lines running to a separate SX1262 radio chip. On the right a single STM32WLE5 block with the SubGHz radio inside it and no SPI connection.

64 KB of RAM and 224 KB of flash

From boards/rak3172.json and boards/tiny_relay.json: stm32wle5ccu, 48 MHz, 65536 bytes of RAM and 262144 bytes of flash. Not all of that flash is left for the application. All four variants set:

board_upload.maximum_size = 229376 ; 32kb for FS

So 224 KB for the app and 32 KB for the filesystem. That is three times less RAM than nRF52 and twenty times less flash than a generously specified ESP32. It bears directly on settings such as MAX_CONTACTS and MAX_NEIGHBOURS, which are set per build target.

One of the four variants has a display (wio-e5-mini). A companion is available over USB only.

How these four compare on compute, memory, connectivity, storage, power and ease of flashing — and which platform suits which role — is covered in MeshCore Platforms.

How the firmware absorbs the four differences technically — which board class each family shares, why RP2040 is the only one without, and why the storage choice is the sharpest dividing line — is covered in Platform realisation.

Sources

Firmware: meshcore-dev/MeshCore, branch main, commit 03b6ef4, 28 July 2026, v1.16.0.

Not from the firmware repo:

  • RP2040 Datasheet, Raspberry Pi Ltd — clock speed, SRAM and flash of the RP2040
  • Espressif datasheets — the specifications per ESP32 sub-SoC

Translated from Dutch by Anthropic Claude