#Arduino simulator deliverable series#

#Arduino simulator deliverable series#

A power trace 4 inches long has only 0.1 Ohms series resistance, usually not significant. Its series resistance is about 25 mOhms/inch. If you have rise times that are short enough or interconnect lengths long enough that require terminations, as long as the traces donвЂ™t go off-board, terminations are just as easy to do for 150 Ohm traces as with 50 Ohm traces, and the power dissipation is less.ДЄ 20 mil wide trace in 1 oz copper can handle 3 A of DC current with no noticeable temperature increase. The characteristic impedance of a 6 mil wide trace using the standard 62 mils thick 2-layer board will be high, on the order of 150 Ohms. Losses donвЂ™t play a role until signal bandwidths are > 1 GHz. In most applications, a series resistance of even 1 Ohm is still transparent. Its resistance per length is 80 millliOhms per inch in 1 oz copper. However, it can carry 1 A of DC current with no discernable temperature rise. You might think that a 6 mil wide trace is too narrow for a signal line. You always want to use the narrowest features you can with no extra cost to get the highest routing density. If you keep to these features you can manufacture your board at any fab shop. These are the smallest features every fab house can manufacture at their lowest price. Habit 1: Use 6 mil wide signal trace, 20 mil wide power traces and 13 mil drilled diameter There are seven habits we can follow that will not guarantee success but will reduce the risk of failure. The more analysis you do, the lower the risk and the higher your confidence that your product will work the first time. Without a detailed analysis, which every engineer should do, we can only follow some general design guidelines that will reduce the risk that these problems will bring your product down. The goal in the physical design of the board, including the layout, is to follow general design guidelines to reduce these two problems. Figure 2 is an example of the measured ground bounce in an Arduino Uno board as multiple digital outputs are simultaneously switched on and off. While there are many signal and power integrity problems that can arise, the two most common and with the largest impact, are cross talk due to excessive mutual inductance between signal and return path loops (ground bounce) and switching noise on the power rails due to large transient current swings. Once the connectivity is established, the interconnects can only screw up the performance of your product. It says nothing about the signal or power integrity performance of the design. The two problems we are trying to avoidДЄ schematic identifies the components used in a design and how they are connected. In my course we use the Arduino as an example of how NOT to design a board and then re-design it using the following Best Design Practices. This unfortunately reinforces bad design habits. You can use almost any design rules and it will work. The Arduino Uno is a pretty robust product. An example of this board is shown in Figure 1. In the graduate class I teach at CU, Boulder, on Practical Printed Circuit Board Design, we use the venerable Arduino Uno board as an example of a 2-layer board that works but violates almost every one of the seven important habits. But, many consumer products, microcontroller and IoT applications are built in 2-layer boards. Generally, it is hard to route a BGA package such as an FPGA or high-end microprocessor in a 2-layer board. In most 2-layer board designs, performance is limited.

But, if performance matters, if the interconnects are not transparent, or if you want to develop good habits, you will want to incorporate these seven habits in your next two layer board design. All you need to worry about is design for manufacturing at low cost and maybe design for test. If you can build your product using a solderless breadboard with wires going every which way, and it works, and the interconnects are transparent, then it probably doesnвЂ™t matter how you design your circuit board.