CMi209

Wiring 1

Overview

CMI209 is a CNC-like module based on the ATmega328P microcontroller. It is controlled by the Soifgo Android app through the CMI (CNC Mobile Interface). Communication is done via a Bluetooth module at a baud rate of 115200.

Note: Before using the Bluetooth module, it must be set to 115200 baud. Wiring 1

The following files are included in the project: PCB file, programmer file, BASCOM file, Proteus file, and reference images. All of these files are available for download at the end of the page.

Saved Settings

The following settings are stored in memory:

pulse=100

This means that 100 pulses move the stepper motor by 1 mm in this project. If you use a different device, adjust the pulses per millimeter value in Soifgo. 

Max_x=40
Max_y=40
Max_z=40

The maximum travel range for the X, Y, and Z axes is 40 mm for this setup. 

feedm=1200

Default movement speed is set to 1400 mm/min. If no speed is received, the module uses the stored/default speed value. 

feeds=5.7

This is the speed correction coefficient used to match the machine behavior. In this device, the measured value is 5.7.

Position Setting Commands

These commands can be received either from G-code or entered manually. Values are in millimeters, and uppercase letters must be used.

Examples:

X12
Y2
Z-3

For X and Y, decimal values, zero, and positive values are allowed. For Z, negative values are also allowed.

Length and width are defined from 0 to their maximum limits. Height has a special meaning because it depends on identifying the work surface. After setting the work surface, the Z axis must be zeroed using: 

resetz

Then, to move the tool to a safe height, for example 5 mm above the surface: 

Z5

To move downward by 1 mm:

Z-1

To zero the X and Y axes:

resetx
resety

Spindle Speed Control

An initial spindle control circuit is included on the board. If you control the module using PWM, do not install the MOSFET input; instead, use the PWM input.

Spindle speed can be set up to 20,000 RPM. The corresponding PWM output range is 0 to 1024 (10-bit). This command can be used in both G-code and manual mode, using uppercase letters. 

S0

Spindle off

S12000

Spindle speed set to 12,000 RPM

Axis Feed Speed

If no initial speed is received, the default speed described above is applied. In both G-code and manual mode, you can send values between 1 and 4800. 

F600

Feed speed: 600 mm/min (uppercase letters)

Reserved PWM Output

Another reserved PWM output is available on the board, near the limit switch pins. It is intended for manual control tasks and can be used for:

The output range is 0 to 1024 (10-bit):

W510

Manual Arc and Circle Drawing

The module supports linear G-code and arc G-code. It also supports a manual method for drawing arcs or circles.

Command Parameters

Example

A full circle with a 10 mm radius at X=20, Y=20, and a depth of 1 mm:

Before this command, raise the tool:

Z5
A0B360X20Y20Z-1

In arc drawing and arc G-code, the number of points used to generate the circle is initially set to 50. If needed, you can reduce it for a polygon-like shape, such as a hexagon, or increase it up to a maximum of 99 for higher precision. 

res23

Sometimes it is necessary to wait before starting an action, for example in plasma cutting where a few seconds of delay may be needed before piercing. The following command creates a delay in seconds, from 1 to 300 seconds: 

sec2

Precise Movement Commands

Sometimes the axes need to move manually in small or large increments. For example, movement in 0.5 mm steps for X, Y, and Z (0.001 to 999) using signed lowercase commands: 

+x0.5
-x0.5
+y0.5
-y0.5
+z0.5
-z0.5

Homing

The home or initial position of the machine is available through: 

G28

and in the module:

home

Both commands move the axes to the home position.

Three normally-open switches should be installed for X home, Y home, and Z home. The Z home switch should allow some extra travel, at least 6 mm to 10 mm, because homing includes position zero and the safe tool height is about 6 mm. Wiring 1

Limit Switches and Emergency Stop Error Input

A dedicated input is provided in the module so that when it is pulled low, the axes, spindle, and the entire machine stop.

In most machines, limit switches are installed at the end of each axis travel so that the machine is not damaged if it moves beyond its allowed range. All switches are wired in parallel, including the emergency stop push button. The circuit and wiring should be done according to the schematic.

When this fault occurs, the module will no longer accept movement commands unless the error is cleared, the machine is power-cycled, or the following command is sent through Soifgo: 

resetall

If the axis remains stuck on the protective limit switch and the fault is not cleared, the module will return to the stop state again.

A dedicated stop command is also available through Soifgo:

stop

When this command is sent, the machine stops and requires: 

resetall

to resume operation.

Stepper Driver Connections

This module uses three stepper motor driver modules. If you want to use another driver, do not install the onboard modules. Instead, use the four pins provided for each axis to connect an external driver: 

GND
ENABLE
STEP
DIR

Video and Usage Sections

Saeid Moghadam

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