ESP8266 Community Forum

- Sun Mar 08, 2015 7:35 am #11574 ESP8266 CBDB Module with MCP4726 12 Bit DAC generating some standard waveforms for testing DAC output accuracy:

Set 0.5V Output:

Fixed 0.5V set

Square Wave Function:

Squarewave waveform

Sawtooth Function:

Sawtooth waveform

Sinusoidal Function:

Sinusoidal waveform

For reference :
http://www.esp8266-projects.com/2015/03/mcp4726-12-bit-i2c-dac-driver-for_7.html

Video:

ESP8266 MPDMv4 AC MAINS Dimmer Home: http://esp8266-projects.com/2016/04/mpdmv4-mains-dimmerswitch-html/
Available on Tindie: https://www.tindie.com/products/nEXT_EVO1/universal-ac-mains-dimmer-mpdmv41/

- Mon Mar 09, 2015 12:40 pm #11668 What is the maximum rate that you can update the DAC? If you wanted to produce the smoothest-possible sawtooth with a 12-bit DAC at 60 Hz, for example, it would require 60 X 4096 X 2 = 491520 updates per second. This is beyond the capabilities of LUA, not to mention the device settling time and even the I2C spec itself.

- Tue Mar 10, 2015 12:52 am #11706

What is the maximum rate that you can update the DAC? If you wanted to produce the smoothest-possible sawtooth with a 12-bit DAC at 60 Hz, for example, it would require 60 X 4096 X 2 = 491520 updates per second. This is beyond the capabilities of LUA, not to mention the device settling time and even the I2C spec itself.

MCP4726 DAC is quite capable with a Settling Time of 6 μs and I2C High-Speed (3.4 Mbps) mode. LUA is the weakest link if you want, but the idea here was to generate some standard waveforms just to be able to proper test driver implementation and the DAC output characteristics.

ESP8266 MPDMv4 AC MAINS Dimmer Home: http://esp8266-projects.com/2016/04/mpdmv4-mains-dimmerswitch-html/
Available on Tindie: https://www.tindie.com/products/nEXT_EVO1/universal-ac-mains-dimmer-mpdmv41/