Reduce heap usage on ST7789 display targets with reduced-memory mode - #10894
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📝 WalkthroughWalkthroughThis PR adds the ChangesOLED Memory Reduction Build Flags
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Updated for a2cdd84 |
caveman99
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Only USE_TFTDISPLAY variants (t1, t096, wismeshtap) compile TFTDisplay.cpp and need the lib's buffer_back; t114 and mesh-solar-tft render through the meshtastic-st7789 driver, which handles the reduced-memory configuration fine - as #10894 (merged from develop) already established by defining the flag there. Remove the -U guard and the per-variant -D (redundant with the arch-wide define in nrf52_base on this branch). Both variants verified building.
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…#10898) * Right-size nRF52 heap tiers after 2.8.0 heap-exhaustion field reports Field reports on 2.8.0 show nRF52840 devices at 99% heap (114/115 KB) within minutes of boot; operator new asserts on OOM, so these devices are one allocation from a reboot. The 2.8.0 cache sizing ladders gave nRF52 the largest non-PSRAM tiers on the assumption that a BLE-only part has a roomy heap - the arena is actually ~125 KB shared with the FreeRTOS task stacks. Per-target retiers (nRF52840 unless noted): - Traffic Management cache 1000 -> 250 entries (10 KB -> 2.5 KB); the unclassified fallthrough drops 1000 -> 400 to match the classic-ESP32 tier (also affects RP2040/RP2350) - Warm node store 200 -> 100 entries (8 KB -> 4 KB); the non-XXAA fallthrough drops 320 -> 100 so an unclassified RAM-constrained part can't boot-allocate 12.8 KB - MESSAGE_HISTORY_LIMIT 20 -> 10 (text pool 4.4 KB -> 2.2 KB), the tier classic ESP32 already ships - MAX_RX_TOPHONE 32 -> 16, shrinking the static packet pool 70 -> 54 slots (~6.6 KB of .bss returned to the heap arena) - PacketHistory hash index off arch-wide (1 KB); O(n) over 240 records is negligible at LoRa packet rates - OLEDDISPLAY_REDUCE_MEMORY arch-wide (~1 KB OLED back buffer); the five TFT variants -U it because TFTDisplay.cpp needs buffer_back for dirty-window diffing - Drop the stale "for testing" 1024-entry TMM override on T1000-E Measured on rak4631: heap arena grows 124,572 -> 131,180 B and boot allocations drop ~15.7 KB, roughly +22 KB free heap on the field-report device class. Migration: the nRF52840 warm flash ring replays through place() (LRU), so the newest 100 identities survive the shrink; the file backend rejects oversized snapshots cleanly (new test covers this). Native suites pass (536/536 Docker, 13/13 native-macos warm store); rak4631, heltec-mesh-node-t114 (TFT) and tracker-t1000-e build green. * Drop stale OLEDDISPLAY_REDUCE_MEMORY -U on t114 / mesh-solar-tft Only USE_TFTDISPLAY variants (t1, t096, wismeshtap) compile TFTDisplay.cpp and need the lib's buffer_back; t114 and mesh-solar-tft render through the meshtastic-st7789 driver, which handles the reduced-memory configuration fine - as #10894 (merged from develop) already established by defining the flag there. Remove the -U guard and the per-variant -D (redundant with the arch-wide define in nrf52_base on this branch). Both variants verified building.
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Sep 5, 2026
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…meshtastic#10898) * Right-size nRF52 heap tiers after 2.8.0 heap-exhaustion field reports Field reports on 2.8.0 show nRF52840 devices at 99% heap (114/115 KB) within minutes of boot; operator new asserts on OOM, so these devices are one allocation from a reboot. The 2.8.0 cache sizing ladders gave nRF52 the largest non-PSRAM tiers on the assumption that a BLE-only part has a roomy heap - the arena is actually ~125 KB shared with the FreeRTOS task stacks. Per-target retiers (nRF52840 unless noted): - Traffic Management cache 1000 -> 250 entries (10 KB -> 2.5 KB); the unclassified fallthrough drops 1000 -> 400 to match the classic-ESP32 tier (also affects RP2040/RP2350) - Warm node store 200 -> 100 entries (8 KB -> 4 KB); the non-XXAA fallthrough drops 320 -> 100 so an unclassified RAM-constrained part can't boot-allocate 12.8 KB - MESSAGE_HISTORY_LIMIT 20 -> 10 (text pool 4.4 KB -> 2.2 KB), the tier classic ESP32 already ships - MAX_RX_TOPHONE 32 -> 16, shrinking the static packet pool 70 -> 54 slots (~6.6 KB of .bss returned to the heap arena) - PacketHistory hash index off arch-wide (1 KB); O(n) over 240 records is negligible at LoRa packet rates - OLEDDISPLAY_REDUCE_MEMORY arch-wide (~1 KB OLED back buffer); the five TFT variants -U it because TFTDisplay.cpp needs buffer_back for dirty-window diffing - Drop the stale "for testing" 1024-entry TMM override on T1000-E Measured on rak4631: heap arena grows 124,572 -> 131,180 B and boot allocations drop ~15.7 KB, roughly +22 KB free heap on the field-report device class. Migration: the nRF52840 warm flash ring replays through place() (LRU), so the newest 100 identities survive the shrink; the file backend rejects oversized snapshots cleanly (new test covers this). Native suites pass (536/536 Docker, 13/13 native-macos warm store); rak4631, heltec-mesh-node-t114 (TFT) and tracker-t1000-e build green. * Drop stale OLEDDISPLAY_REDUCE_MEMORY -U on t114 / mesh-solar-tft Only USE_TFTDISPLAY variants (t1, t096, wismeshtap) compile TFTDisplay.cpp and need the lib's buffer_back; t114 and mesh-solar-tft render through the meshtastic-st7789 driver, which handles the reduced-memory configuration fine - as meshtastic#10894 (merged from develop) already established by defining the flag there. Remove the -U guard and the per-variant -D (redundant with the arch-wide define in nrf52_base on this branch). Both variants verified building.
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Summary
This PR enables the
meshtastic-st7789driver's reduced-memory mode on the ST7789-based targets that use it today:heltec-mesh-node-t114heltec-vision-master-t190m5stack-cardputer-advheltec-mesh-solar-tftThe change is limited to PlatformIO env flags:
-DOLEDDISPLAY_REDUCE_MEMORYWhy
Runtime heap usage on larger ST7789 displays is heavily impacted by the driver's display buffering. On the T114, the display path was the main reason heap usage was so high.
These targets all use the same
meshtastic-st7789driver, which already supports a lower-memory mode.Expected impact
This should reduce runtime heap by removing the extra ST7789 backbuffer used by these targets.
Approximate savings by panel size:
320x240: about9.6 KB320x170: about7.0 KB240x135: about4.1 KBNo intended UI or feature changes beyond using less heap.
Testing
Verified locally:
platformio run -e heltec-mesh-node-t114The other targets were updated in the same way because they use the same ST7789 driver path and reduced-memory flag.
Summary by CodeRabbit