dig:lab_4_ardu
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— | dig:lab_4_ardu [2016/03/13 16:52] – [Schematics Instructions] tobi | ||
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+ | ===== Lab 4 ====== | ||
+ | In [[lab_3]] we built a prototype of our microphone-servo board. Now let's design the schematic of our own PCB. We'll draw a schematic of the microphone amplifier and servo supply and connector from lab 3, using the PCB design tool KiCad (formerly we used Eagle). It is not a very super powerful tool but installs very quickly, can run on multiple platforms, and has lots of user-developed parts libraries. We'll start today the layout of this board and you have time during next week to complete it and send by email. | ||
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+ | ** This is an individual exercise and each student must complete it on their own laptop. ** | ||
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+ | ==== Preparation (before lab exercise) ==== | ||
+ | |||
+ | - See [[pcb]] for the links to download the PCB design software. | ||
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+ | |||
+ | ===== Schematics Instructions ===== | ||
+ | |||
+ | In this exercise we'll draw an Eagle schematic of the microphone amplifier and servo supply / connector from [[lab_3]]: | ||
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+ | {{dig: | ||
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+ | Remember that you actually modified some resistor values in lab_3 to bring the LM324 output more in the middle of it working range (see datasheet extract below). | ||
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+ | - Install Eagle - see [[pcb]]. | ||
+ | - Open the Eagle dashboard by launching Eagle. | ||
+ | - Open the {{dig: | ||
+ | - Modify your components if you want. To do this you have to find your parts at libraries: gates (symbols) for a resistor, polarized capacitor, LM324 opamp, microphone, and 3 pin header. | ||
+ | - Delete the unused symbols. | ||
+ | - Wire up the parts according to the sketch above. | ||
+ | - Ensure your designators and values are correct. | ||
+ | - Place a large label indicating the design name and designer name (your name). | ||
+ | ---- | ||
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+ | When you are finished with your board schematic, send your schematic file (.sch) to [[tobi@ini.phys.ethz.ch? | ||
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+ | |||
+ | === LM324 tip === | ||
+ | The LMC6484 is a rail to rail input and output opamp. However, the input range of the LM234 is limited: | ||
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+ | {{dig: | ||
+ | |||
+ | === Data sheets === | ||
+ | |||
+ | * {{dig: | ||
+ | * {{dig: | ||
+ | * {{dig: | ||
+ | * Ultra capacitor, http:// | ||
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+ | |||
+ | ===== Layout Instructions ===== | ||
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+ | |||
+ | Now let's do the layout of our PCB. We'll use the layout part of Eagle, along with perhaps the footprint editor and autorouter. | ||
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+ | Let's turn your schematic into a daughterboard for the Arduino Nano board. Please observe the following points: | ||
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+ | - You will be doing a 2-layer daughterboard. Therefore your power must be routed in the signal layers. Pay attention that you try to keep the power routing to the digital and analog parts separate except where they join at the connections to a ground pin from the nano board header. | ||
+ | - Keep sensitive electrical nodes far away from the noisy digital servo control. | ||
+ | - Place at least one bypass capacitor near the microphone preamplifier circuit. | ||
+ | - Don't put components over the nano board. | ||
+ | |||
+ | You may find it helpful to again scan the {{dig: | ||
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+ | Below shows the template board layout. | ||
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+ | {{dig: | ||
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+ | When you are finished with your board schematic and layout, send a zip/tgz archive of your design to [[tobi@ini.phys.ethz.ch? | ||
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+ | Here you have a screenshot of a possible solution that uses 2 layers. Polygons have been used for GND (bottom) and 3.3v (top). | ||
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+ | {{: | ||
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+ | ~~DISCUSSION~~ |
dig/lab_4_ardu.txt · Last modified: 2024/02/29 07:28 by 127.0.0.1