Neotron Pico

The Neotron Pico is micro-ATX sized Neotron, powered by a Raspberry Pi Pico microcontroller board. The Raspberry Pi Pico is fitted with a Raspberry Pi RP2040 microcontroller - a dual-core Cortex-M0+ with 256 KiB of SRAM. The Raspberry Pi Pico also has a 2 MiB external QSPI flash.

Whilst the Cortex-M0+ cores are only ARMv6-M compatible (not ARMv7E-M or even ARMv7-M), there were some very compelling advantages in making the switch. For example, compared to the Texas Instruments Tiva-C Launchpad on the Neotron 32, the Raspberry Pi Pico:

• Has two cores instead of one
• Is clocked at 133 MHz instead of 80 MHz (and actually, many units run happily at 250 MHz)
• Has 256 KiB of SRAM instead of 32 KiB
• Costs £3.60 instead of £15.00
• Has hardware designed to generate digital RGB video
• Can drive an I²S audio codec

Form Factor

The Neotron Pico is a micro-ATX sized board - 244mm x 170mm. It is designed to fit into any micro-ATX or ATX compatible PC case, and includes headers for a reset switch, power switch, power LED and status LED. It provides four card-edge expansion slots, which provide access to the SPI and I²C buses. Each slot has a unique IRQ line and SPI Chip Select, avoiding the classic IBM PC problem of allocating resources to expansion cards.

Links

• Hardware: https://github.com/Neotron-Compute/Neotron-Pico
• BIOS: https://github.com/Neotron-Compute/Neotron-Pico-BIOS
• Raspberry Pi Pico
  • Datasheet: https://datasheets.raspberrypi.org/pico/pico-datasheet.pdf
• Raspberry Pi Silicon RP2040
  • Datasheet: https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf
  • Hardware Design Guide: https://datasheets.raspberrypi.org/rp2040/hardware-design-with-rp2040.pdf

Features

• CPU: Dual 133 MHz 32-bit ARM Cortex-M0+ CPU cores
• RAM: 256 KiB of internal SRAM
• Video Output: Super-VGA
  • 640x480 @ 60 Hz (gives a 80x30 text mode)
  • 640x400 @ 70 Hz (gives a 80x25 text mode)
  • 256 colours from a pallette of 4,096
  • RGB video buffer for genuine 75 Ohm output
  • Has ESD protection circuit with VGA DDC level-shifter
• Audio: 16-bit 48 kHz audio input and output (line-in, mic-in, line-out and headphone-out)
  • Uses Texas Instruments TLV320AIC23BPW audio codec
  • Has triple 3.5mm jack, plus AC'97 header and extra four-pin line-in header
• Storage: SD/MMC Slot
• USB: One USB Full-speed OTG port
• Dedicated board management controller (BMC), supporting
  • Two PS/2 ports (keyboard and mouse)
  • Standby mode and PSU control
  • System reset
• Expansion: Four Expansion Slots (with SPI and I²C)
• RTC: MCP7940N Real-Time Clock with backup battery