I’ll create a structured takeover report covering both boards, architecture, completed work, current live state, known blockers, recovery history, verification gates, and the exact order a new engineer should follow.
PCB Engineering Takeover Report1. Purpose and release status
This is the engineering handoff for the two-board KRYSTAL drone companion system. It consolidates the design intent, current implementation, known defects, routing history, verification evidence, and the recommended recovery sequence.
Current release status: HOLD — neither board is approved for fabrication or flight.
The next engineer should treat all counts in this report as the last confirmed state and rerun live ERC/DRC/layout checks before making changes. Do not generate Gerbers until every release gate in Section 13 passes.
Power, camera, radar, autopilot, Wi‑Fi, FHSS and SIYI interfaces
Board dimensions, stackups and enclosure direction
Completed fixes and verified checks
Routing-service failure and recovery history
Known footprints, software and regulatory risks
Recommended takeover sequence
Fabrication-release gates
Immediate first-day checklist and required engineer deliverables
The report clearly marks both boards HOLD for fabrication until routing, interface freeze, DRC, thermal, software and mechanical validation are complete.
The Singapore contract adds a dual-band Wi-Fi requirement:
IEEE 802.11ac/a/b/g/n
2.412 GHz – 2.472 GHz and/or 5.15 GHz – 5.825 GHz
2 dBi dual-band antenna
Candidate module under review: AP6256 dual-band 802.11ac Wi-Fi + Bluetooth module. Its datasheet indicates IEEE 802.11a/b/g/n/ac support, 2.4 GHz and 5 GHz operation, SDIO host interface, and small antenna reference of 0–2 dBi peak gain. Confirm Singapore IMDA approval path, allowed 5 GHz sub-bands, DFS/TPC obligations if applicable, and whether the exact module/antenna combination has acceptable modular approvals before production release.
SIYI A8 Mini Air Unit RF Review
The candidate SIYI A8 Mini payload includes an air unit specified by the customer as 5.100–5.825 GHz with a 5 dBi standard omni antenna. This must be handled as a separate RF emitter from KRYSTAL's onboard Wi‑Fi/LoRa design.
Regulatory actions:
Confirm the exact SIYI air-unit model, firmware region, rated TX power, modulation/bandwidth, and certification IDs.
Confirm whether 5 dBi antenna gain is permitted with the air-unit TX power without exceeding EIRP limits.
Verify coexistence with KRYSTAL's planned dual-band Wi‑Fi, especially in 5 GHz operation.
Record whether the air unit is supplied as an already-approved subsystem or must be included in LOWALT's product approval package.
Safety Radio / GCS Link RF Review
Customer-provided secondary safety radio:
Table
Item
Value
GCS
RadioMaster TX16S Mark II 4IN1
Protocols
FrSky / Spektrum family through internal 4IN1 module
Frequency band
2.400–2.4835 GHz
EIRP
<100 mW
Regulatory / integration actions:
Confirm Singapore/IMDA acceptance for the exact RadioMaster TX16S Mark II 4IN1 regional configuration.
Confirm the matching drone-side receiver model, antenna gain, protocol, and certification status.
Include the receiver/onboard radio, not only the GCS transmitter, in the full product RF coexistence plan.
Evaluate 2.4 GHz coexistence with KRYSTAL Wi‑Fi/Bluetooth and any SIYI or payload RF equipment.
Define failsafe behavior when the safety-radio link is lost, degraded, or overridden by autopilot logic.
SIYI HM30 / MK32 Data & Video Link RF Review
Customer-provided tertiary data/video link:
Table
Item
Value
GCS / link
SIYI HM30 / MK32
Frequency band
5.500–5.600 GHz required; verify exact device supports/locks to this range
Power
<320 mW EIRP required
Architecture role
Tertiary IP data/video link
Preliminary compatibility:
Architecturally suitable as an external data/video link because HM30/MK32-class systems provide Ethernet/IP and RTSP-style video workflows.
It is separate from KRYSTAL's onboard Wi‑Fi module and separate from the SIYI A8 Mini camera payload, though it may carry the A8 Mini's RTSP video.
Regulatory cautions:
Vendor material often lists 25 dBm / 320 mW transmit power; this may be conducted RF power, not EIRP. With antenna gain, EIRP can be higher than 320 mW.
Confirm exact antenna gain, region mode, firmware, conducted TX power, and certification IDs.
Check Singapore/IMDA authorization for 5.5–5.6 GHz operation, including any DFS/TPC/channel restrictions.
Confirm coexistence with KRYSTAL dual-band Wi‑Fi and any 5 GHz SIYI payload air unit.
Status
Draft — created when LoRaWAN capability was added to the schematic.
Wireless Technology Summary
Table
Module
Designator
Technology
Frequency Band
Host Interface
Notes
Ezurio/Laird RM1262 / 453-00139R
U6
LoRaWAN / LoRa
902–928 MHz RM1262; RM126x family also covers 863–870 MHz variants
UART with RTS/CTS
Module uses MHF4 RF connector; final antenna, region SKU, and certification evidence must be locked before release.
Applicable Regulatory Tracks
FCC Part 15 / modular transmitter integration rules for US operation.
ISED for Canada if sold or operated there.
CE RED for EU operation; confirm correct 868 MHz regional variant and duty-cycle/channel-plan limits.
UKCA if sold in the UK.
RF Design Notes
Use the certified module integration guide and allowed antenna list for final antenna selection.
Keep the LoRa module antenna/RF connector at the board edge with copper keepout under/around the RF area per module datasheet.
Do not place high-current switching loops, Ethernet magnetics, or noisy clock traces near the LoRa antenna path.
The module RESETN pin is internally pulled to a 1.8 V domain and must not be driven directly by 3.3 V logic without level-compatible circuitry.
Region selection matters: 915 MHz for US-style operation, 868 MHz for EU-style operation.
Required Documentation Checklist
Wireless module identified in schematic: U6 453-00139R.
Confirm exact regional SKU and certification IDs.
Confirm antenna MPN and gain against module certification conditions.
Add antenna mechanical/RF keepout to PCB layout.
Confirm final LoRaWAN channel plan and transmit-power limits in firmware.
Export final schematic, BOM, PCB layout, and test reports before certification submission.
Open Items
Final antenna and enclosure are not selected.
Ethernet and compute-board architecture are provisional.
S32K344 pin mux for LoRa UART and expansion buses must be verified against the NXP IOMUX/reference manual.