IO Mapping

nXPico M exposes an IO e Modem module under the device node. Digital and analog channels are identical to nXPico, on the same GPIOs — an application that only uses I/O runs unchanged.

Digital Inputs

Channel	Parameter ID	Type	GPIO	Default mapping
Input 0	1000	BIT	GP2	IN0
Input 1	1001	BIT	GP3	IN1
Input 2	1002	BIT	GP6	IN2
Input 3	1003	BIT	GP7	IN3
Input 4	1004	BIT	GP20	IN4
Input 5	1005	BIT	GP21	IN5
Input 6	1006	BIT	GP22	IN6

Digital Outputs

Channel	Parameter ID	Type	GPIO	Default mapping
Output 0	2000	BIT	GP10	OUT0
Output 1	2001	BIT	GP11	OUT1
Output 2	2002	BIT	GP8	OUT2
Output 3	2003	BIT	GP9	OUT3
Output 4	2004	BIT	GP14	OUT4
Output 5	2005	BIT	GP15	OUT5

PWM outputs

The six digital outputs can be driven as PWM outputs at runtime, exactly as on nXPico — same channels, same pins, same behaviour.

Channel	Parameter ID	Drives
PWM_ENABLE	9100	bit n = output n in PWM
PWM0…PWM5	9000‑9005	level 0…65535 of GP10, GP11, GP8, GP9, GP14, GP15

PWM_ENABLE := 2#0000_0100;   (* OUT2 becomes a PWM output *)
PWM2       := 32768;         (* 50% duty *)

The carrier frequency is a device parameter, one per pair of outputs: 9200 for OUT0/OUT1, 9201 for OUT2/OUT3, 9202 for OUT4/OUT5. Range 9 Hz…100 kHz, default 2289 Hz, and the duty stays 0…65535 whatever you choose.

The LED stays out of this

nXPico M has no PWM_LED channel: its LED is a WS2812 driven over PIO, and it already has a per-colour level in the LED channel.

That is also why the three pairs are clean here: each one maps to a whole PWM slice, without the LED-versus-OUT3 precedence that nXPico inherits from having its LED on GP25.

The full explanation — resolution against frequency, why the pairs share a setting, how to measure it with a multimeter — is on the nXPico page.

Analog Inputs

12-bit ADC, raw value 0…4095 over 0…3.3 V.

Channel	Parameter ID	Type	GPIO	ADC	Default mapping
Analog 0	3000	WORD	GP26	ADC0	AN0
Analog 1	3001	WORD	GP27	ADC1	AN1
Analog 2	3002	WORD	GP28	ADC2	AN2

RGB LED

Channel	Parameter ID	Type	GPIO	Default mapping
LED RGB	4000	DWORD (output)	GP23	LED

The LED is a WS2812 addressable RGB, driven by the RP2350’s PIO. The channel is a DWORD in 0x00RRGGBB form, not a bit:

LED := 16#00FF0000;    // red
LED := 16#0000FF00;    // green
LED := 16#00000040;    // dim blue
LED := 0;              // off

Why not GP25

On this board GP25 is WL_GPIO2 and drives the modem’s buck converter — it is not an LED. Writing to it would be, at best, useless.

No TEMPERATURE channel

Unlike nXPico and nXPico W, nXPico M does not expose the die temperature. The RP2350’s internal sensor still exists in silicon; it is simply not declared in this device description.

Modem channels

Six channels form a transparent AT pipe to the nRF9151: the low-level way to use the modem, where the runtime does not interpret the protocol. An IEC library for the modem is in development. See Modem, with examples.

Channel	Parameter ID	Type	Dir	Role
MODEM_OUTPUT	7000	64 bytes	OUT	command bytes, terminated by the first zero
MODEM_INPUT	7001	128 bytes	IN	128-byte window over the response
MODEM_INPUT_LEN	7002	WORD	IN	total bytes received so far
MODEM_SEND	7003	WORD	OUT	rising edge: 1 append and transmit, 2 append only
MODEM_RESET_INPUT	7004	WORD	OUT	1 clears the receive buffer
MODEM_INPUT_OFFSET	7005	WORD	OUT	moves the read window

Startup parameters

Three parameters in the device’s Internal Parameters tab, applied by the driver before the bus cycle starts:

Parameter	ID	Type	Meaning
Modem system mode	8000	USINT	0 = LTE-M, 1 = NB-IoT, 2 = both
Modem APN	8001	STRING	sets AT+CGDCONT
Modem SIM PIN	8002	STRING	empty = no PIN

The SIM PIN is never written to the log — only “accepted” or “rejected”.

System

Channel	Parameter ID	Type	Access	Value
Vendor	393218	STRING	read-only	'nexo S.r.l.'
Model Name	393219	STRING	read-only	'IO'

IO e Modem is the name of the node in the device tree, not the value of this parameter.