User guide

Cortex Microcontroller and VEXnet Joystick User Guide
Page 13 of 14
10. Analog Information: Analog lines are input only and read about 0.2 volts when open. Circuit details are as
follows:
a. Analog input range is 0 to +5 volts.
b. Analog to digital resolution is 12-bit, compiler resolution may vary.
c. Analog circuit has a 470k pull-up to +5 volts, a series 10k resistor and a 20k resistor to ground.
d. Analog inputs also have a 1000 pF capacitor to ground on the processor side of the 10k resistor.
e. 3 dB bandwidth: 16 kHz.
f. Circuit connections as shown.
Weak Pull-up
In Processor
Digital Input Output
1000 PF
3.3 V
1 K
Digital Port
Analog Input
(Typical)
To Processor
20K
1000 PF
470 K
10 K
+5 V
Analog Port
11.DigitalInformation:Whenconguredasaninput,digitallineshaveaweakpull-up. When congured as an output,
digital lines drive 0 volts for a low and 3.3 volts for a high. Circuit details are as follows:
a. Digital input range is 0 to +5 volts.
b. Digital drive is primarily limited by the 1k series resistor, so it can output a 2v high into 2k-ohms to ground or a 0.8v
low into 7k-ohms to 3.3v.
c. Digital inputs also have a 1000 pF capacitor to ground on the processor side of the 1k resistor.
d. 3 dB input bandwidth: 150 kHz.
e. Circuit connections as shown.
12.CircuitdetailsoftheDigital-to-AnalogPort,SP:
a. Circuit SP is connected to the Digital-to-Analog-Converter (DAC) output of the User Processor.
b. Factory default Hex le does not support the DAC output. Check your compiler for availability and use.
c. SP is an Analog Output when congured by compiler. Drive is primarily limited by a 5 kilo-ohm internal processor
resistance and by the 100 ohm series resistor. Output swing of the processor into an open load is 0.2v to 3.1v, typical.