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| projects:esp [2015/02/04 18:22] – [I2C bus] darron | projects:esp [2017/01/12 22:44] (current) – external edit 127.0.0.1 | ||
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| The three devices are a Microchip MCP23016 digital I/O expander, NXP PCF8591 ADC/DAC and Microchip 24LC512 EEPROM. | The three devices are a Microchip MCP23016 digital I/O expander, NXP PCF8591 ADC/DAC and Microchip 24LC512 EEPROM. | ||
| - | These were chosen because they add useful capabilities to the ESP-01 or RPi and all three are available in DIP format from CPC in the United Kingdom. | + | These were chosen because they add useful |
| + | You may also consider adding an I2C RTC to this project and perhaps it shall be updated to include one at a later time. | ||
| === Schematic === | === Schematic === | ||
| - | The circuit is expected to be used with either an ESP-01 attached and with it' | + | The circuit is expected to be used with either an ESP-01 attached and with its UART connected to a computer to load in scripts, else without an ESP-01 and with the I2C lines connected to a Raspberry Pi. |
| {{: | {{: | ||
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| === I2C bus === | === I2C bus === | ||
| - | The I2C bus is simple affair with only two lines required for it' | + | The I2C bus is simple affair with only two lines required for its operation. This is perfect for the ESP-01 module which only has two GPIOs exposed on its header pins. For the Raspberry Pi, there are two I2C buses, but only one is normally available. |
| ^Address ^Device | | ^Address ^Device | | ||
| Line 44: | Line 45: | ||
| </ | </ | ||
| === MCP23016 === | === MCP23016 === | ||
| + | |||
| + | The MCP23016 is general purpose digital I/O expander. There are more modern and faster varieties of this device but as yet they are not available at CPC. | ||
| ^Control ^Register ^Function | | ^Control ^Register ^Function | | ||
| Line 57: | Line 60: | ||
| == ESP-01 NodeMcu == | == ESP-01 NodeMcu == | ||
| - | First we need eSPY, fetch and build it. The examples | + | The NodeMcu firmware can be controlled via a serial console. This can be a manual operation else with a specially written tool for the job: eSPY. |
| + | |||
| + | First we need to fetch eSPY, and then build it. The examples | ||
| < | < | ||
| hg clone http:// | hg clone http:// | ||
| Line 101: | Line 106: | ||
| </ | </ | ||
| - | The script comes with the eSPY application and can be demomstrated | + | The script comes with the eSPY application and can be demomstrated |
| < | < | ||
| ./mcp.esp | ./mcp.esp | ||
| Line 135: | Line 140: | ||
| === PCF8591 === | === PCF8591 === | ||
| + | |||
| + | The PCF8591 combines 4 analogue inputs and a single analogue output. The inputs can be more than simple input channels but this isn't looked at here. | ||
| + | |||
| ^Control ^Register | ^Control ^Register | ||
| |0 | channel 0 |Read ADC 0| | |0 | channel 0 |Read ADC 0| | ||
| Line 180: | Line 188: | ||
| </ | </ | ||
| - | When the script is run with eSPY we can see the DAC output ramp up and a running | + | When the script is run with eSPY we can see the DAC output ramp up with a running |
| < | < | ||
| 0 | 0 | ||
| Line 215: | Line 223: | ||
| I2C EEPROMs have varied addressing schemes. The simplest is a 8-bit address offset, another one where a block selection is made with an I2C address and a byte selection is made with an 8-bit address offset. Yet another, where the I2C address is fixed but it now has a 16-bit address offset and lastly one with both of the last methods combined. | I2C EEPROMs have varied addressing schemes. The simplest is a 8-bit address offset, another one where a block selection is made with an I2C address and a byte selection is made with an 8-bit address offset. Yet another, where the I2C address is fixed but it now has a 16-bit address offset and lastly one with both of the last methods combined. | ||
| - | The 24LC512 | + | The 24LC512 |
| == ESP-01 NodeMcu == | == ESP-01 NodeMcu == | ||
| Line 259: | Line 267: | ||
| 238 | 238 | ||
| </ | </ | ||
| - | |||
| - | eSPY is still being developed and as yet doesn' | ||
| == RPi == | == RPi == | ||
| Line 292: | Line 298: | ||
| [[http:// | [[http:// | ||
| [[http:// | [[http:// | ||
| + | |||
