Getting Started

nXPico M runs the same CODESYS Control runtime as nXPico, with two additions of its own: the WS2812 RGB LED and the nRF9151 cellular modem, used through a transparent AT pipe (an IEC library for the modem is in development).

The board must already be running the CODESYS runtime before you open CODESYS.

1. Install the device description

1. Download CODESYS_Control_Pico2_M.devdesc.xml.
2. In CODESYS: Tools → Device Repository → Install…
3. Select the file and confirm.

Name	nXPico M
Vendor	nexo S.r.l.
Device ID	167e 2008
Version	3.5.20.111

2. Create a project and add the device

1. File → New Project… → Standard project.
2. Pick nXPico M.
3. An IO e Modem module appears under the device node: digital I/O, analog inputs, the RGB LED and the modem channels. See IO Mapping.

3. Connect and log in

Connect over USB-C — the CODESYS gateway runs on USB. The modem plays no part in programming the device.

At the first login CODESYS asks you to create the administrator user: the board has no default users or passwords. See Users and Passwords.

What differs from nXPico

	nXPico	nXPico M
Digital I/O, analog inputs	identical	identical
LED	BIT on GP25	DWORD 0x00RRGGBB, WS2812 on GP23
TEMPERATURE channel	present	absent (product decision)
Serial ports	COM2 + COM3	COM3 only — UART0 belongs to the modem
Modem	—	6 I/O channels (AT pipe); 3 startup parameters; IEC library in development
X.509 functions	— (nXPico W only)	available

Runtime limits

Same as the rest of the family:

Setting	Value
Cyclic IEC tasks	3 — a fourth one is refused with an error at download or at startup
Max task priority	31
Default cycle time	100 ms
Code + constants (flash)	1 MB, executed in place (XIP)
Data (variables)	20 KB
I/O image	1280 bytes input, 1280 bytes output
Online change	Not supported — full download only
Applications	1 (Application)
Force / write variables	Supported
Breakpoints	Not available — see below

Task priorities are honoured: a higher-priority task interrupts a lower-priority one that is running.

The code, up to 1 MB, is written to flash sector by sector during the download. If the download is interrupted (for example by unplugging the USB cable), no application starts at the next boot: never a half-written one.

Breakpoints. The board is protected by secure boot, and the chip’s protection disables debugging: the red dot appears in the IDE, but execution does not stop. Monitoring, writing and forcing variables remain available.

Division by zero

A 32-bit integer division (INT, DINT, UDINT, …) by zero returns 0 with no exception: that is how the Cortex-M33 processor behaves. A 64-bit division (LINT, ULINT, LWORD) by zero, and floating-point errors computed in software, put the application into an exception instead (EXCEPTION state in the IDE); the runtime stays reachable. To catch the 32-bit division as well, use CODESYS’s POUs for implicit checks (CheckDivDInt, CheckDivInt, CheckDivReal, CheckDivLReal, …).

Next: IO Mapping, Modem, Serial Ports, X.509 and ST Examples.