SCPI Parameter Syntax

Quiescence Rule — No Queries During a Benchmarked Test

Send no SCPI commands while a streaming or iperf2 test is running. Every
query preempts the data path you’re measuring (USB SCPI = priority 7; TCP
SCPI runs on the WifiTask itself), so polling skews the result.

The firmware preserves end-of-test stats in IDLE: IPERF:STATs? returns
gCtx.last_stats (frozen by FinalizeStats); STR:STATS? survives across
StopStreamData until the next StartStreamData or STATS:CLEar.

Pattern: start → time.sleep(duration + margin) → single STATS query.

For progress visibility on long runs, use an out-of-band signal (Saleae,
PC-side iperf2.log) — never poll the device under test.

List of SCPI Commands

IEEE 488.2 Standard Commands

Error and Status Commands

OPERation Condition Register Bits

The firmware sets these bits in the OPER condition register to reflect real-time device state:

Bits are set on STR:START and cleared on STR:STOP.

QUEStionable Condition Register Bits

The firmware sets these bits in the QUES condition register to reflect streaming health:

QUES bits are set in real-time during streaming and cleared when streaming stops. The QUES CONDition register reflects current health; the QUES EVENt register latches transitions (clears on read).

System Commands

Power Commands

BQ24297 Battery Charger Diagnostics

DIO Commands

DIO Debug Probe Commands

Lightweight framework for toggling or pulsing DIO pins from anywhere in the streaming pipeline to enable logic-analyzer timing analysis. While a probe is assigned to a DIO channel, that channel is owned exclusively — normal DIO:PORt:STATe / DIO:PORt:DIRection / PWM commands on an owned channel are rejected with -200 Execution error. Clearing a probe restores the user-configured state automatically.

Two probe classes:

• Standard probes 0–9 mapped 1:1 to DIO_0..DIO_9, permanently wired to streaming pipeline stages, controlled at runtime via these SCPI commands.
• Ad-hoc probes 10–15 mapped 1:1 to DIO_10..DIO_15, compile-time only (set bits in DIO_PROBE_ENABLE_MASK in BoardConfig.h).

Standard probe map — hardcoded call sites:

Modes:

• OFF — inert, no toggles
• TOGGLE — flip pin on each call (use for event rate / cadence capture)
• PULSE — drive HIGH on PulseStart, LOW on PulseEnd (use for duration capture)

Caps-only abbreviations: DIOProbe abbreviates to DIOP (not DIOPR). ASSign → ASS, CLEar → CLE, PIPELine → PIPEL. E.g. SYST:DIOP:ASS 0,TOGGLE.

See docs/PIPELINE_TIMING.md in the firmware repo for captured timing measurements and per-stage CPU-budget tables.

PWM Commands

WiFi Commands

Note: Commands marked Requires WiFi powered return SCPI_ERROR_EXECUTION_ERROR when WiFi is disabled (STANDBY mode). Configuration SET commands and queries for settings (SSID?, NETType?, SECurity?) work in any power state. In STA mode with DHCP, ADDRess?, MASK?, and GATEway? return DHCP-assigned values; use the CONFigure: variants to read user-configured values.

WiFi Command Notes

• The device creates an open WiFi access point by default with SSID “DAQiFi”
• WiFi must be enabled (ENAbled 1) and applied (APPLY) for changes to take effect
• Settings must be saved (SAVE) to persist across power cycles
• The device must be in POWERED_UP state (power state 1) for WiFi to operate
• Post-APPLY timing: the WiFi module takes time to re-initialize, associate/start, obtain DHCP, and reopen the TCP server on port 9760. Allow up to ~20 s before attempting a client TCP connection — pinging may succeed earlier than TCP accepts, and ADDR? may report the DHCP IP before the TCP server is actually listening. A handy readiness pattern: after APPLY, poll ADDR? until it returns a non-default IP, then attempt connect(ip, 9760) with a short retry loop.
• APPLY is a soft restart, NOT a hardware reset. Internally APPLY triggers WIFI_MANAGER_EVENT_REINIT which the state machine handles by BSSDisconnect + reconnect with new settings — it explicitly avoids WDRV_WINC_Deinitialize (Microchip driver bug: leaves the chip in permanent reset; see wifi_manager.c:867). APPLY does not toggle the WINC’s CHIP_EN / RESET_N GPIOs.
• WINC hardware reset path: use SYST:COMM:LAN:HRESet. Internally fires WIFI_MANAGER_EVENT_DEINIT → WDRV_WINC_Close → WDRV_WINC_Deinitialize → wifi_manager_FixWincResetState() (asserts CHIP_EN, deasserts RESET_N on the WINC GPIO pins) → 2 s settle → WIFI_MANAGER_EVENT_INIT to bring the chip back up cleanly. Validated 2026-04-28: recovers a wedged outbound TCP stack within ~25 s. Symptoms requiring this: ICMP ping still works but TCP connect() from MCU times out indefinitely. Returns immediately; poll LAN:ADDR? until non-192.168.1.1 to confirm DHCP completed.
• *RST now also resets the WINC. From the v3.4.6+ firmware, the *RST handler fires wifi_manager_Deinit() before RCON_SoftwareReset, so the WINC chip GPIO reset and the PIC32 soft reset happen together — the user gets the expected “everything fresh” state. Earlier firmware left the WINC running with stale state across *RST.
• Recovery hierarchy (least to most invasive):
  1. SYST:WIFI:IPERF:STOP — clears iperf2 module’s gCtx; rarely sufficient
  2. LAN:APPLY — soft restart; refreshes association but leaves WINC chip state untouched (does not recover wedge)
  3. SYST:POWer:STATe 0 → 1 — cycles 10V rail; doesn’t drive WINC reset GPIOs (does not recover wedge)
  4. SYST:COMM:LAN:HRESet — drives DEINIT → GPIO reset → INIT; recovers wedged TCP stack ✓ validated
  5. *RST — full PIC32 reset; on v3.4.6+ also drives WINC reset GPIO via the bundled wifi_manager_Deinit ✓
  6. Physical power cycle — last resort. Required only if even the GPIO reset doesn’t recover (rare; see #384 for ongoing investigation).
• Manual ENA 0 / APPLY / ENA 1 / APPLY recipe is NOT reliable. Earlier wiki revisions described this as the recovery path. Empirical testing (2026-04-28) showed it sometimes works and sometimes doesn’t, depending on what state the WiFi state machine is in. Use LAN:HRESet instead.

Automatic SSID/Hostname MAC Suffix

When the SSID or hostname is the bare default “DAQiFi”, the firmware automatically appends the last 4 hex digits of the device’s MAC address to make each device distinguishable on the network (e.g. “DAQiFi-95A7”). This applies to:

• AP SSID: The broadcast network name visible to WiFi clients
• DHCP hostname: The device name reported to routers and network discovery tools (DHCP Option 12)

The suffix is applied on every WiFi init and reinit (including after APPLY), so factory resets and default values always get the suffix. User-customized values (anything other than bare “DAQiFi”) are preserved without modification. The HOST? and SSID? queries return the suffixed values.

iperf2 Commands

Quiescence rule applies. Query IPERF:STATs? once after the run; firmware returns last_stats in IDLE.

IPERF:STATs? Response Fields

IPERF:DIAGnostics? Response Fields

Mode 5 — TX-blast notes

• Server-mode: device binds and listens on the requested port, PC connects. Duration starts at accept, not bind, so the user has time to start the PC reader after sending the SCPI.
• Throughput is the upper bound for any iperf2 mode — protocol overhead is zero (raw 1400-byte payloads from a static buffer). PC and device byte counts agree to ≤2% (E: 2026-05-02 5×60s battery).
• Stats schema is the same as iperf2 modes — Bytes, DurationMs, KBps populate at session end via FinalizeStats.

ADC Commands

Capabilities Discovery

DAC Commands (NQ3 Only)

Voltage Output Precision

Precision Values:

Board-Specific Defaults:

Notes:

• Applied systemwide: CSV streaming, JSON streaming, and SCPI voltage queries (MEAS:VOLT:DC?, SOUR:VOLT:LEV?)
• Protobuf streaming is unaffected
• Can be changed while streaming is active; takes effect on the next encoded sample
• Use CONF:DATA:SAVE to persist across reboots; otherwise resets to board default

SPI Commands

Streaming Commands

Streaming Statistics Response Fields

SYSTem:STReam:STATS? returns the following key=value pairs:

Session lifecycle: Stats are cleared automatically when a new streaming session starts (STR:START). They are preserved after STR:STOP so the user can query them. A LOG_E summary is automatically written at session end if any data was lost (retrieve via SYSTem:LOG?).

Thread safety: 64-bit counters use critical sections for atomic updates on 32-bit PIC32MZ. STATS? returns an atomic snapshot of all fields. TimerISRCalls lives in a separate volatile global written only by the timer ISR (priority 1, no concurrent writers); the snapshot read is taken inside the same critical section, which blocks the timer ISR for coherent 64-bit access.

Diagnostic logic for TimerISRCalls:

• TimerISRCalls < freq × duration → timer is rate-limited (PIC32MZ ~90 kHz hardware ceiling for the streaming ISR + Harmony dispatch)
• TimerISRCalls == TotalSamples + QueueDropped → every ISR is fully accounted for between the ISR and the deferred task
• QueueDroppedSamples > 0 → sample pool exhausted (encoder/output too slow for the rate the timer is firing)
• UsbDroppedBytes / SdDroppedBytes > 0 → encoder is fine but transport can’t keep up

Per-interface coverage: WiFi has full pipeline tracking (BytesSent/BytesConfirmed/SendErrors/PartialSends) because the radio transport is non-deterministic. USB and SD only track buffer overflow drops — their transports are deterministic (USB CDC is protocol-ACKed, SD writes are synchronous), so “sent == confirmed” by definition.

Test Pattern Streaming Mode

Test pattern mode replaces real ADC values with synthetic data for deterministic regression testing and benchmarking. The real ISR timing is preserved — patterns only override the ADC value field.

SCPI Commands:

SYSTem:STReam:TEST:PATtern <pattern>   # Set pattern (0=off, 1-6)
SYSTem:STReam:TEST:PATtern?            # Query current pattern

Pattern Types:

• adcMax = max raw ADC code = Resolution – 1 (4095 for MC12bADC 12-bit, 262143 for AD7609 18-bit)
• Pattern is runtime-only (not persisted to NVM, resets on reboot)
• Sample counter resets at each STR:START for deterministic sessions
• All encoding formats and output interfaces work normally with test patterns

Streaming Throughput Benchmarking

Benchmark Mode Usage:

1. Enable test patterns: SYST:STR:TEST:PATtern 2
2. Enable benchmark mode: SYST:STR:BENCHmark 1
3. Start streaming at desired rate: SYST:STR:START 11000
4. Wait, then stop: SYST:STR:STOP
5. Check results: SYST:STR:STATS?
6. Restore: SYST:STR:BENCHmark 0

Measured Zero-Loss Throughput Ceilings (NQ1, test patterns):

Dynamic Memory Management Commands

Buffer sizes and sample pool depth are configurable at runtime to optimize RAM usage for specific streaming scenarios. All settings take effect at the next STR:START. Settings are runtime-only (not persisted to NVM, reset on reboot to safe defaults). All setters reject changes while streaming is active.

Memory Diagnostics Response Fields

SYSTem:MEMory:FREE? returns a comma-separated key:value response:

Auto-Balance Algorithm

SYSTem:MEMory:AUTO queries the active streaming interface (SYSTem:STReam:INTerface) and SD enable state, then allocates default buffer sizes only for enabled interfaces. Remaining streaming pool space goes to the sample pool (clamped 100-2000). Also re-partitions the 124KB coherent pool among all three DMA consumers (SD write, USB write, WiFi SPI staging) — inactive interfaces get minimums, active interfaces split remaining space (SD 50%, USB 30%, WiFi 20%; single-active gets everything). Returns the allocation as "USB:<n>,WiFi:<n>,SD:<n>,Encoder:<n>,Pool:<n>,UsbDma:<n>,WifiDma:<n>,SdDma:<n>".

SD Logging Commands

SD Card INFO Response Example:

3,"SD",SR256,8.4,2818572288,2023/6

Fields: MID=3 (SanDisk), OID=”SD”, Product=”SR256″, Revision=8.4, Serial=2818572288, Date=2023/June

SD Card Logging Example:

SYSTem:POWer:STATe 1
SYSTem:STORage:SD:ENAble 1
SYSTem:STORage:SD:FILE "test.csv"
SYSTem:STReam:INTerface 2      // Set output to SD card
SYSTem:STReam:FORmat 2          // CSV format
CONFigure:ADC:CHANnel 0,1
SYSTem:STReam:START 100
// Data logs to SD card
SYSTem:STReam:STOP
SYSTem:STORage:SD:LISt?         // File appears in listing
SYSTem:STORage:SD:GET "test.csv"
SYSTem:STORage:SD:DELete "test.csv"

FreeRTOS Commands

Common Usage Examples

Basic Power Control

# Power up the device
SYSTem:POWer:STATe 1

# Check power state
SYSTem:POWer:STATe?

# Get system info
SYSTem:INFo?

# Power down
SYSTem:POWer:STATe 0

WiFi Configuration

# Configure WiFi to connect to a network
SYSTem:COMMunicate:LAN:SSID "MyNetwork"
SYSTem:COMMunicate:LAN:SECurity 3
SYSTem:COMMunicate:LAN:PASs "MyPassword123"
SYSTem:COMMunicate:LAN:NETType 1
SYSTem:COMMunicate:LAN:APPLY

# Save settings to NVM
SYSTem:COMMunicate:LAN:SAVE

# Configure as Access Point
SYSTem:COMMunicate:LAN:NETType 4
SYSTem:COMMunicate:LAN:SSID "DAQiFi-AP"
SYSTem:COMMunicate:LAN:SECurity 0
SYSTem:COMMunicate:LAN:APPLY

ADC Data Acquisition

# Enable channel 0 for 10V range
ENAble:VOLTage:DC 0,1
CONFigure:ADC:RANGe 0,10

# Read single voltage
MEASure:VOLTage:DC? 0

# Start streaming at 100Hz
SYSTem:STReam:START 100

# Stop streaming
SYSTem:STReam:STOP

Digital I/O Control

# Enable DIO port
DIO:PORt:ENAble 1

# Set as output
DIO:PORt:DIRection 0,1

# Set high
DIO:PORt:STATe 0,1

# Read state
DIO:PORt:STATe? 0

PWM Output

# Enable PWM channel 0
PWM:CHannel:ENable 0,1

# Set 1kHz frequency
PWM:CHannel:FREQuency 0,1000

# Set 50% duty cycle
PWM:CHannel:DUTY 0,50

SD Card Logging

# Power up
SYSTem:POWer:STATe 1

# Enable SD card and set filename
SYSTem:STORage:SD:ENAble 1
SYSTem:STORage:SD:FILE "data.csv"

# Set streaming to SD interface and CSV format
SYSTem:STReam:INTerface 2
SYSTem:STReam:FORmat 2

# Enable ADC channel(s)
CONFigure:ADC:CHANnel 0,1

# Start logging at 100 Hz
SYSTem:STReam:START 100

# Stop and retrieve data
SYSTem:STReam:STOP
SYSTem:STORage:SD:LISt?
SYSTem:STORage:SD:GET "data.csv"

Note: WiFi does not need to be disabled for SD logging. However, WiFi streaming (SYSTem:STReam:INTerface 1 or 3) cannot be used simultaneously with SD logging due to shared SPI bus. WiFi firmware update is also blocked while SD is busy.

Source of truth: daqifi/daqifi-nyquist-firmware wiki → 01-SCPI-Interface · Edit on GitHub · this page is auto-synced; edit upstream to update.