IoT Fire Alarm Device Design
Thought for 8 sec
You should ask Quectel / supplier for the EC25MXGA hardware design package, not just the marketing datasheet.
Ask for:
-
EC25MXGA Hardware Design Guide
- Full pin descriptions
- Power supply requirements
- PWRKEY / RESET timing
- UART / USB / SIM / RF reference circuits
- VDD_SDIO usage guidance
-
Recommended PCB land pattern / footprint
- Pad dimensions
- Pad numbering
- Paste mask / solder mask recommendations
- Keepout zones under/around the module
- Assembly notes
-
Reference schematic
- VBAT_RF / VBAT_BB decoupling
- SIM socket wiring
- Antenna matching / ESD
- Status pins
- Power-on/off sequence
-
RF layout guidelines
- 50 Ω antenna routing
- Ground stitching via recommendations
- Antenna connector/matching network placement
- Diversity/GNSS pins if used or unused
-
Certification documents
- RCM / ACMA / AS/CA S042 relevance
- Carrier approval info for Australia
- LTE band support for AU carriers
- Test reports if available
-
Lifecycle / supply confirmation
- Active production status
- Recommended replacement if EC25MXGA is not preferred
- Minimum order / lead time
Short message you can send:
We are designing a dual-modem Australian fire alarm signalling device using 2 × EC25MXGA. Please provide the EC25MXGA hardware design guide, recommended PCB land pattern/footprint, reference schematic, RF layout guide, SIM interface recommendations, VDD_SDIO connection guidance, Australian carrier/certification documentation, and lifecycle/supply status.
Ok I’ll contact them
Thought for 14 sec
Good plan. Ask them specifically for the hardware design guide + recommended PCB land pattern for EC25MXGA-128-SNNS.
Until we get that, the safest path is:
- Keep EC25MXGA in the design.
- Do not send the PCB to manufacture yet.
- Continue with placement/routing cleanup only as a draft.
- Finalize modem footprint, SIM wiring, RF layout, and
VDD_SDIOtreatment once Quectel confirms the official guidance.
Clean draft layout
Review EC25 wiring
Check power budget
Update factory checklist
Run current checks
Refine this doc
Ask about this doc
AS4428 / ASE Installation & Documentation Checklist
Sources
- User screenshots of AS4428.6 documentation/design clauses, OCR-extracted.
- User-uploaded
ti-0157_Fire-Alarm-Signalling-Equipment-Installation-Checklist.pdf, OCR-extracted. - Critical values must be verified against the official standards and installation authority requirements.
AS4428.6 documentation deliverables
Installation and user documentation must be prepared and include at least:
Equipment description
- General description of the ASE equipment.
- Functions relating to other parts of the AS4428 series and AS7240 series.
- Ancillary functions not required by the standard.
Technical specifications
Provide sufficient mechanical, electrical, and software compatibility information for other system components, including:
- Power requirements for recommended operation.
- Maximum number of FDAS/FAS inputs per ASE: design target is 8.
- Maximum and minimum electrical ratings for each input and output.
- Communication parameters for each transmission path.
- Recommended cable parameters for each transmission path.
- Fuse ratings.
Installation information
- Suitability for use in different environments.
- Environmental basis from screenshot: components expected to operate when external environmental conditions conform to IEC 60721-3-3 Class 3k5.
- Design should be traceable to a quality management system; AS/NZS ISO 9001 is noted in the screenshot as an example.
Fault indication requirements extracted from screenshots
- ASE transmission-path faults must be reported to the monitoring centre.
- Faults must be indicated by a separate LED and/or alphanumeric display field.
- Transmission-path fault indicator flashes when detected and goes steady after monitoring-centre acknowledgement.
- Faults between ASE and FDAS must be detected within 100 seconds.
- Telecommunication-path faults between ASE and monitoring centre must be detected within 100 seconds.
- Telecommunication-path fault indication must not be suppressed during a fire alarm condition.
- If some transmission-path fault indications are suppressed during fire alarm condition, they must be revealable manually at Access Level 1 or 2.
- ASE must automatically reset fault reporting/display once the fault clears.
- Correct functional indication must be restored within 30 seconds after the fault clears.
TI-0157 / Firemon-style installation requirements relevant to this design
FDCIE / ASE input interface
- ASE connects to FDCIE relay contacts via a 470 Ω resistor board for monitoring:
- Fire Alarm
- System Fault
- Disconnected / Isolated
- Power Fault
- Example RM3119 mapping:
- Input 1: Alarm
- Input 2: System Fault
- Input 3: Isolated / Disconnected
- Input 4: Power Fault
- Inputs 5–8: additional alarms, configurable as primary alarm or secondary/fault behavior.
- FDCIE interface uses SPDT relay contacts.
- This adds a second input-interface mode to track alongside the older Centaur multi-voltage EOL ladder.
Power
- RM3119 example operates from 8–30 VDC.
- Power connector example: P7 pin 4 negative, pin 5 positive.
- Installation checklist requires the ASE low-voltage threshold to be approximately 10% below the actual DC supply voltage.
- Our design target remains 12–24 VDC nominal, but power front end should tolerate and/or intentionally handle the wider 8–30 V style installation environment if required.
Communications paths
- Two communications paths are required.
- Example: primary Telstra, secondary Optus.
- Both paths must meet AS1670.3 reliability requirements.
- Installation/configuration checklist expects both SIMs installed before commissioning.
- Both path signal strengths must be checked.
- For 4G connectivity, signal strength must be -109 dBm or greater for each path.
Antennas
- Two external antennas required.
- Example uses Benelec 024584 4G/5G antennas connected to SMA-terminated antenna leads.
- Antennas must not be mounted within 200 mm of a person’s head.
- Antennas must not be mounted inside the FDCIE cabinet.
- Antennas must not be mounted near other equipment antennas.
- The two ASE antennas must be suitably separated from each other.
- Antenna cable should be kept as short as possible, or low-loss cable used.
- Antennas must not be installed where susceptible to vandalism.
- Antenna type/location must provide suitable signal level in all operating bands.
- 3 m or 5 m coaxial cable may be used where needed, but signal loss must be considered.
- Lightning and surge protection should be installed where required.
- Penetrations must be sealed and waterproofed.
LCD / local indication
- LCD should display Normal status.
- LCD should show primary path P signal meter and secondary path S signal meter.
- LCD should indicate ALM, FLT, DIS, and PWR during input testing.
- Signal meter behavior in checklist includes flashing/not flashing and up/down arrow status; exact UI behavior can differ but must clearly show path status.
Commissioning / test requirements
- Before operational use, checklist must be completed and signed.
- End-to-end testing must exercise primary and secondary communication paths and signal strength.
- All connected inputs must be tested.
- Test mode must be supported and controlled.
- During commissioning, each relevant input is activated, verified locally on LCD, confirmed by monitoring/fire station, then cleared.
- Reconnection after disconnection requires retesting and reporting.
Resistor board / contact quality checks
- Checklist requires measuring voltage drop across each input terminal pair on the resistor board.
- Requirement: voltage drop must be less than 10 mV while associated FDCIE relay contacts are normally closed.
- If voltage drop exceeds 10 mV, inspect wiring, moisture/corrosion, loose/incorrect terminations, and relay contact condition.
Design implications for our schematic
- Include enough ADC/digital input flexibility to support both:
- Centaur-style multi-voltage supervised input decoding, and
- Firemon/RM3119-style 470 Ω resistor board relay interface.
- Provide local LCD states for ALM, FLT, DIS/ISO, PWR, Normal, modem path P/S status, signal strength, and path faults.
- Add explicit per-path fault outputs/events in firmware for modem/SIM/network failures.
- Provide test/isolate mode via Dallas/iButton key and log all mode changes.
- Add hardware/firmware support for low-voltage threshold configured approximately 10% below measured installation supply.
- Keep antenna outputs as external pigtail-to-panel connections, likely SMA panel connectors.
- Include documentation fields for fuse ratings, cable requirements, input/output electrical ratings, and communication parameters.
Open design decision
The project now has two historical input styles in the requirements:
- Older Centaur-style multi-state input voltage bands.
- RM3119/Firemon-style 470 Ω resistor board with separate inputs for Alarm/Fault/Isolate/Power and optional Inputs 5–8.
Before final schematic, decide whether the product must support both modes, or only the newer 470 Ω resistor board method.
Sources
AS4428.6 documentation deliverables
Equipment description
Technical specifications
Installation information
Fault indication requirements extracted from screenshots
TI-0157 / Firemon-style installation requirements relevant to this design
FDCIE / ASE input interface
Power
Communications paths
Antennas
LCD / local indication
Commissioning / test requirements
Resistor board / contact quality checks
Design implications for our schematic
Open design decision
