Rpi Pico Board with RP2040 MCU

The RP2040 has 264KB of onboard RAM, FLASH is external QSPI.

_images/pinouts.jpg

RP2040 Negatives

Why I don’t use this MCU

  1. It has no Flash. External SPI nust be used which raises the BOM cost and complexity, plus SPI Flash is slow.

  2. RTC: One of the flaws in the RP2040’s design is that its RTC has no ability to take battery backup.

  3. RTC: The time is always lost on mcu reset.

  4. ADC: Due to a silicon design problem, it has a lot of noise which reduces the effectice resolution to 8 bits

  5. VREF: there is no hi accuracy VREF on the chip

  6. Watchdog: is timing out in half the specified time

RP2040 Chip features

Dual ARM Cortex-M0+ @ 133MHz
264kB on-chip SRAM in six independent banks
Support for up to 16MB of off-chip Flash memory via dedicated QSPI bus
DMA controller
Fully-connected AHB crossbar
Interpolator and integer divider peripherals
On-chip programmable LDO to generate core voltage
2 on-chip PLLs to generate USB and core clocks
30 GPIO pins, 4 of which can be used as analog inputs
Peripherals
    2 UARTs
    2 SPI controllers
    2 I2C controllers
    16 PWM channels
    USB 1.1 controller and PHY, with host and device support
    8 PIO state machines

Mecrisp Stellaris Pico

Official release. It’s a port of Mecrisp-Stellaris and is much the same, hardware differences excepting. Lots more information in the tarball below.

  • Serial terminal on UART0

  • 115200 Baud 8N1

  • TX - pin 1

  • RX - pin 2

https://sourceforge.net/projects/mecrisp/files/mecrisp-stellaris-2.5.6.tar.gz

The Pico Mandlebrot Challenge

Note

New Release @ 4 Mar 2021. Now with Mandlebrot and Tricorn Set plus a breathing LED cosine effect while waiting for keypress. Still in only 252 Bytes !

https://sourceforge.net/projects/mecrisp-stellaris-folkdoc/files/2021_03_01_mandelboot.tar.gz

  • This bootable binary is only 252 Bytes! can you make a smaller one ?

  • Serial terminal on UART0

  • 115200 Baud 8N1

  • TX - pin 1

  • RX - pin 2

_images/mandleboot-dual.jpg