The GRBL Project

A few months ago, the Raspberry Pi Foundation announced the RasPi Pico board and ARM RP20240 chip that powers it. The Pico sells for $4 and is bit more powerful than the STM32F104 in the (in)famous Blue Pill makers love. But, in a package that will be consistent, unlike all the variants of the Blue Pill.

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The RP2040 is a dual processor ARM Cortex M0 chip. One of the powerful features is its programmable I/O - PIO.  Without going into the details, PIO is like having a number of tiny embedded computers that can take all work out of I/O operations and leave the main CPUs for real time response.

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The grblHAL team is working an RP2040 port as we speak and I have been working on breakout board to use it.  Here is the current feature set.

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• 4 Axis

• Isolated 12V limit and control switches

• Spindle PWM, Direction, Enable, 0-10V (non-isolated) outputs.

• Relay drivers for Spindle, Dust Extractor, Flood, Mist and 3 Auxiliary Relays.

• 5V and 12V relay voltage options.

• 8 Auxiliary outputs (3 with aforementioned relay drivers, 5 TTL/SSR capable)

• Dust Extractor Relay ganged with Spindle Relay.

• Switch pin header for independent Dust Extractor control.

• UART header with 3.3V/5V voltage select and extra enable pin

• I2C header (3.3V only).

• SPI header (3.3V only), set up for an SDCard.

• Daughter board header mounts for UART, I2C and SPI. 

• Pluggable Screw Terminals - horizontal and vertical supported. I may make a design using smaller/cheaper terminals or pin headers.

• Power inputs for 12V and isolated 12V for limits and control inputs.

• LED indicators for both power inputs.

• 5V regulator on board.

• 5V sharing between USB and onboard +5V (both may be connected at same time).

• Both 12V circuits may be joined together via jumpers.

• Reset switch.