/z80-retro-i2cspi

Z80-Retro! I2C/SPI Master Interface Board & Driver Library

Primary LanguageHTMLGNU Lesser General Public License v2.1LGPL-2.1

Z80-Retro! I2C/SPI Master Interface Board & Driver Library

An addon I2C/SPI master interface board that uses the Z80-Retro! parallel printer port and a bit-banged driver library to interact with the I2C/SPI ports. KiCad design files are also included.

Description

Driver Library

i2cspi_lib.asm - This driver library includes all necessary routines to communicate with I2C and SPI hardware devices using the Z80-Retro! parallel port. Extensive comments and protocol descriptions are provided to help understand the library. The library requires the retromon.sym symbol table from the z80-retro-monitor project.

PCB Hardware

An I2C/SPI master interface board using bit-bang techniques and utilizes the Z80-Retro! parallel printer port. The PCB design includes 4 I2C ports and 4 SPI ports. The I2C ports are all common and the SPI ports include 4 individual chip select (CS) lines. Requires +5vdc be connected from the Z80-Retro! or an external power supply.

  • A PDF version of the schematic can be found here.
  • Build of Materals (aka BOM) can be found here.

PCB Layout

PC Board Image

I2C Timing Capture

I2C Timing

SPI Timing Capture

SPI Timing

Help

Library Common Routines

ACTIVE_LED - Set the ACTIVE LED on the I2C/SPI interface board on or off

I2C Routines

I2C_INIT - Initialize I2C status variables and the Z80-Retro! PRN_DAT port
I2C_START - Initiate I2C communication with a START condition
I2C_STOP - Stop I2C communication with a STOP condition
I2C_SEND_BIT - Send a bit over the I2C bus
I2C_READ_BIT - Read a bit on the I2C bus
I2C_SEND_BYTE - Send a byte to the I2C bus
I2C_READ_BYTE - Read a byte from the I2C bus
I2C_SEND_STREAM - Send a byte stream to the I2C bus
I2C_READ_STREAM - Read a byte stream from the I2C bus

SPI Routines

SPI_INIT- Initialize the SPI MODE, bit transfer order and the Z80-Retro! PRN_DAT port
SPI_SEND_BYTE - Send 8 bits to the SPI port and discard the received data
SPI_READ_BYTE - Read 8 bits from the SPI port
SPI_CSx_TRUE - Assert the select line initialized in SPI_INIT (CS1 - CS4) supported
SPI_CSx_FALSE - De-assert the select line initialized in SPI_INIT (CS1 - CS4) supported
SPI_SEND_STREAM - Send a stream of bytes to the SPI port
SPI_READ_STREAM - Read a stream of bytes from the SPI port

Several example routines are included to test the various functions. Everything is heavily commented explaining the library routines and how to use them. These include:

  • ad_test.asm - test a NXP Semiconductors PCF8591 I2C A/D-D/A converter
  • eeprom_test.asm - test a generic 24C256 I2C EEPROM
  • gpio_test.asm - test a NXP Semiconductors PCF8574 I2C 8-bit GPIO expander
  • led_test.asm - test an Analog Devices MAX7219 LED driver in SPI mode 0
  • oled_test.asm - test a generic SSD1306 128x64 SPI 0.96" OLED display
  • spi_test.asm - test an Analog Devices ADXL345 accelerometer in SPI mode 3

Author

Kenny Maytum - KRSynthWorx

Version History

  • v1.0 - Driver Library
    • Initial Public Release
  • v2.0 - KiCad Design Files
    • Initial Public Release

License

This project is licensed under the [GNU Lesser General Public License] - see the LICENSE file for details

Acknowledgments

Inspiration, code snippets, libraries, etc.