Member #385542

Member Since: December 3, 2012

Country: United States

  • I tweaked the Adafruit SSD1306 library to work with this screen.

    With hardware SPI on my Teensy 3.1, the SparkFun library takes 935 microseconds to update the screen, but the Adafruit library can do it in 625 microseconds.

  • This sensor works acceptably with bright sources, for example reading the average color of a TV, or a bank of LEDs, but it is not very sensitive when trying to use the onboard LED's reflection to detect the color of objects.

    Something like the retired SEN-08924 (TCS230 based) or a newer TCS3472 seems to work much better for that application....

  • They probably forgot to update the features list, 3.0 had 4 channels, 3.1 has 16.

  • Mixed-Signal integration verified that there would be no problems shifting the range.

    "The formula is: fo=1/(R*C) Hz

    The clock to corners are:

    Filter 1: 2620:1 Filter 2: 1030:1 Filter 3; 410:1 Filter 4: 156:1 Filter 5: 66:1 Filter 6: 26:1 Filter 7: 10:1"

    I'd like to try interleaving two chips for more total bands, I'll be curious to see if it is noticeable, or if the bands overlap so much it won't be useful.

  • I had good luck with this chip by running the input from my 3.3v powered electrete microphone through an op amp set up as a unity buffer, and then through a second set up as a log amplifier (pair of diodes between output and inverting input) to implement kind of auto gain control. Make sure to use an op-amp that can go rail-to-rail and play nice with low voltages. Try various types of diodes to change the volume gain curve. Then in software I implemented auto muting and un-muting of channels so little pops wouldn't show up occasionally, combined the data from the upper two channels since my microphone did not capture much high frequency, and added some additional level normalization. Next time around I want to try a microphone with AGC built in, and see if that is easier.

    Here is my code and schematics:

  • Note: The MSGEQ7 chips I ordered from eBay were all defective, replacements from sparkfun worked perfectly. Be careful, or you might waste time troubleshooting defective chips!

  • When using a 200k resistor and 33pf capacitor to select the oscillator frequency, what frequency should I be measuring on pin 8? Would I see 165khz like specified in the datasheet? Or is that frequency only present somewhere else internally on the chip?

No public wish lists :(