Data Sheet

3/8/2018 Arty Z7 Reference Manual [Reference.Digilentinc]
https://reference.digilentinc.com/reference/programmable-logic/arty-z7/reference-manual 16/24
The Arty Z7 board includes two tri-color LEDs, 2 switches, 4 push buttons, and 4 individual LEDs as shown in Figure 12.1. The push
buttons and slide switches are connected to the Zynq PL via series resistors to prevent damage from inadvertent short circuits (a short
circuit could occur if an FPGA pin assigned to a push button or slide switch was inadvertently defined as an output). The four push buttons
are “momentary” switches that normally generate a low output when they are at rest, and a high output only when they are pressed. Slide
switches generate constant high or low inputs depending on their position.
(https://reference.digilentinc.com/_detail/reference/programmable-logic/arty-z7/arty-z7-gpio.png?id=reference%3Aprogrammable-logic%3Aarty-
z7%3Areference-manual)
Figure 12.1. Arty Z7 GPIO ().
The four individual high-efficiency LEDs are anode-connected to the Zynq PL via 330-ohm resistors, so they will turn on when a logic high
voltage is applied to their respective I/O pin. Additional LEDs that are not user-accessible indicate power-on, PL programming status, and
USB and Ethernet port status.
The Arty Z7 board contains two tri-color LEDs. Each tri-color LED () has three input signals that drive the cathodes of three smaller
internal LEDs: one red, one blue, and one green. Driving the signal corresponding to one of these colors high will illuminate the internal
LED (). The input signals are driven by the Zynq PL through a transistor, which inverts the signals. Therefore, to light up the tri-color LED
(), the corresponding signals need to be driven high. The tri-color LED () will emit a color dependent on the combination of internal LEDs
that are currently being illuminated. For example, if the red and blue signals are driven high and green is driven low, the tri-color LED () will
emit a purple color.
Digilent strongly recommends the use of pulse-width modulation (PWM) when driving the tri-color LEDs. Driving any of the inputs to a
steady logic ‘1’ will result in the LED () being illuminated at an uncomfortably bright level. You can avoid this by ensuring that none of the
tri-color signals are driven with more than a 50% duty cycle. Using PWM also greatly expands the potential color palette of the tri-color led.
Individually adjusting the duty cycle of each color between 50% and 0% causes the different colors to be illuminated at different intensities,
allowing virtually any color to be displayed.
The on-board audio jack (J13) is driven by a Sallen-Key Butterworth Low-pass 4th Order Filter that provides mono audio output. The
circuit of the low-pass filter is shown in Figure 14.1. The input of the filter (AUD_PWM) is connected to the Zynq PL pin R18. A digital
input will typically be a pulse-width modulated (PWM) or pulse density modulated (PDM) open-drain signal produced by the FPGA. The
signal needs to be driven low for logic ‘0’ and left in high-impedance for logic ‘1’. An on-board pull-up resistor to a clean analog 3.3V rail
will establish the proper voltage for logic ‘1’. The low-pass filter on the input will act as a reconstruction filter to convert the pulse-width
modulated digital signal into an analog voltage on the audio jack output.
12.1 Tri-Color LEDs
13 Mono Audio Output