docs(tt_um_georgboecherer_vco): digital pin specs corrected in info.y…

…aml, documentation extended in docs/info.md

projects/tt_um_georgboecherer_vco/docs/info.md

@@ -9,12 +9,18 @@ You can also include images in this folder and reference them in the markdown. E
 
 ## How it works
 
-A voltage controlled oscillator (VCO).
+A voltage controlled oscillator (VCO) using 4 differential stages and a bias controller. At each stage, the outputs are low-pass filtered by nfet transistors connected as capacitors to ground. 
+
+The first analog pin `ua[0]` can be used as input to control the frequency by changing the gate voltages of nfet current sources connected to ground. The second analog pin `ua[1]` can be used to monitor the gate voltage generated by the bias controller of the pfet current sources connected to VDD. Alternatively, the second analog pin `ua[1]` can be used as input pin to overwrite the bias controller.
+
+The 4 differential stages provide in total 8 tap signals with phase differences of 360/8. The 8 tap signals are converted to digital signals by buffers and output at the 8 digital output pins `uo[0]` to `uo[7]`. *NB:* the 8 tap signals are ordered by wiring convenience, not by phase.
+
+For further information, see [github.com/gbsha/tt08-analog-vco](https://github.com/gbsha/tt08-analog-vco/) for updated information.
 
 ## How to test
 
-Connect a control voltage to the input pin and observe the oscillating signal at the output pin.
+Connect a control voltage or current to the analog input pin `ua[0]` and observe the oscillating signals at the digital output pins.
 
 ## External hardware
 
-DC power supply for the control voltage, oscilloscope for monitoring the output.
+DC power supply for the control voltage/current, oscilloscope for monitoring the outputs.

projects/tt_um_georgboecherer_vco/info.yaml

@@ -3,7 +3,7 @@ project:
   title:        "Analog Voltage Controlled Oscillator"      # Project title
   author:       "Georg Boecherer"      # Your name
   discord:      "georgboecherer"      # Your discord username, for communication and automatically assigning you a Tapeout role (optional)
-  description:  "A voltage controlled oscillator"      # One line description of what your project does
+  description:  "A voltage controlled oscillator with 4 differential stages."      # One line description of what your project does
   language:     "Analog" # other examples include Verilog, Amaranth, VHDL, etc
   clock_hz:     0       # Clock frequency in Hz (or 0 if not applicable)
 
@@ -24,24 +24,24 @@ project:
 # The pinout of your project. Leave unused pins blank. DO NOT delete or add any pins.
 pinout:
   # Inputs
-  ui[0]: "bit in 0"
-  ui[1]: "bit in 1"
-  ui[2]: "bit in 2"
-  ui[3]: "bit in 3"
+  ui[0]: ""
+  ui[1]: ""
+  ui[2]: ""
+  ui[3]: ""
   ui[4]: ""
   ui[5]: ""
   ui[6]: ""
   ui[7]: ""
 
   # Outputs
-  uo[0]: "bit out 0"
-  uo[1]: "bit out 1"
-  uo[2]: "bit out 2"
-  uo[3]: "bit out 3"
-  uo[4]: ""
-  uo[5]: ""
-  uo[6]: ""
-  uo[7]: ""
+  uo[0]: "tap 0 signal"
+  uo[1]: "tap 1 signal"
+  uo[2]: "tap 2 signal"
+  uo[3]: "tap 3 signal"
+  uo[4]: "tap 4 signal"
+  uo[5]: "tap 5 signal"
+  uo[6]: "tap 6 signal"
+  uo[7]: "tap 7 signal"
 
   # Bidirectional pins
   uio[0]: ""
@@ -54,12 +54,12 @@ pinout:
   uio[7]: ""
 
   # Analog pins - make sure to also set "analog_pins" above, else the pins won't be connected
-  ua[0]: "control signal"
-  ua[1]: "optional control signal"
+  ua[0]: "bias control signal"
+  ua[1]: "optional bias control signal"
   ua[2]: ""
   ua[3]: ""
   ua[4]: ""
   ua[5]: ""
 
 # Do not change!
-yaml_version: 6
+yaml_version: 6