In such cases, you would have to create your own custom parts for both the schematic and possibly the footprint.
One of the most challenging aspects of designing a circuit in EDA software when there components that you need is not available. I then transferred the schematic to Eagle CAD. I started off by looking at Neil's hello.ftdi.44 board, tracing through the wiring and sketching the schematic for the board on paper. I've configured PB2 as an outpout pin to sink current from the LED when it is turned on. For my circuit, I have used a 499 ohm resistor to limit the current through the LED to about 6 mA. The circuit diagrams below show the 2 methods of interfacing LEDs to a digital output pin. use the digital output pin as a current sink use the digital output pin to source current to the LED There are also 2 common ways of connecting LEDs to digital inputs: LEDs are normally configured with a current limiting resistor to limit the amount of current passing through it to between 10~25 mA typically. Newer, high intensity LEDs may have forward voltage drops of 3.2~3.3V. Traditionally, LEDs have a forward voltage drop of 1.7V. Light emitting diodes (LEDs) are special types of diodes which emit monochromatic light when a current passes through it. When the switch is pressed, the digital input will read a logic 1 and when the pushbutton is released, the digital input will read a logic 0 because of the pull-down resistor.įor my circuit, I've elected to use a 10k pull-up resistor to tie the digital input pin (PA7) to Vcc. use a pull-down resistor to tie the digital input to ground and connect the pushbutton between the digital input pin and Vcc. When the pushbutton is released, the digital input reads a logic 1. In this configuration, everytime the pushbutton switch is pressed, the digital input will be pulled low. use a pull-up resistor to tie the digital input to a logic 1 and connect the pushbutton between the digital input pin and ground. There are 2 basic ways to interface a pushbutton switch to a digital input on an embedded controller. For this assignment, we make use of 2 of the pins to interface to a pushbutton switch and an LED. The remaining pins on the ATTiny44 can be used to interface to other peripherals.
We use an FTDI USB-to-TTL serial device for communications. It has a 2x3 IDC header for programming and a 1圆 SIL header for communicating with another computer over a serial link. The echo hello-world board uses an ATTiny44 embedded controller. Try out different EDA software to design our hello-world boardįor extra credit, we could simulate the operation of the board.Redraw the echo hello-world board, adding (at least) a push button and an LED (with current limiting resistor.Exercise 06 - Electronics Design Assignmentįor our assignment for this week, we have been set the following: