Button board

MPW3 Bringup / Characterization

Experiments in bringing up SKY130 MPW-3 chips from the initial tapeout in November 2021. Similarly to MPW-1, the standardized "Caravel" padframe used in this tapeout had hold-time violations between

Breakout PCBs

• Characterization PCB Schematic

  • Independent voltage regulators for padframe and core (with non-volatile memory)
  • DS1077LU-50 clock generator with 50kHz - 50MHz output frequency + non-volatile memory
  • MCP23017 GPIO expanders for scanning chip I/Os
  • MCP1319 reset supervisor
  • MicroMod-style socket for Caravel chip breakout

• FTDI Breakout Schematic

  • Connects characterization PCB to FT232RL for UART access over USB
  • Includes LEDs, switches, and SPI FRAM for use with picoRF0 CPU

• VGA Breakout Schematic

  • Breaks out infinite-runner game and pong game to a 2-bit VGA DAC
  • Includes buffer chips for

Repo Structure

• boards/ - KiCAD design files for breakout PCBs
• parts/ - I/O characterization results for several dies
• scripts/i2c_iface.py - Script for interfacing with the voltage regulators, clock generator, and GPIO expanders on the characterization board
• programs/ - Programs for running on the Caravel processor for the different applications
  • aes_test.c - Test the AES core on crypto-accelerator-chip-v2 design
  • gpio_config_io_dino.py - GPIO configuration for the VGA runner game
  • gpio_config_io_pong.py - GPIO configuration for the VGA pong game
  • picorf0_test.c - Test program for the picoRF0 custom CPU core
  • read_ident.c - Reads the ROM identifier and build number in the SHA and AES cores
  • sha256_test.c - Test the SHA256 core with some test vectors
  • spi_fram.c - Test program for using the Caravel SPI master to interface with an FRAM chip
  • uart_working.c - Workaround for UART RX on MPW-3 Caravel