Copying a Reference Circuit

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Overview

This tutorial will guide you through copying a reference circuit into tscircuit.

There are many great reasons to copy a reference circuit:

• You are learning tscircuit and want to focus on learning the tscircuit tools rather than designing a circuit
• You are migrating a project from another EDA tool
• You are planning on making a modified version of an existing circuit

In this guide we’ll walk through the four major steps of copying a reference circuit:

1. Understanding your reference circuit
2. Importing or creating each subcomponent
3. Connecting your subcomponents together

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0. Prerequisites

1. You’ve initialized a directory with tsci init
2. You can successfully see the default circuit using tsci dev
3. You have a typescript IDE like VS Code installed

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1. Understanding your reference circuit

Most reference circuits are composed of one or more of the following elements:

1. Pictures of the manufactured board
2. A PDF of the schematic
3. A Bill of Materials or description containing the major parts

Use these resources to find part numbers for each component in your schematic. You’ll need this because you’ll need to create a typescript component for each part you’re using (except for passives like resistors and capacitors)

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2. Importing or creating each subcomponent

You should create a file in the lib directory for each subcomponent in your design. There are generally 3 ways you can create components.

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2.1 Super Easy Mode: Find it on JLCPCB

The easiest way to create a component is to google “jlcpcb <part name>” and find the part on JLCPCB. You then can copy the JLCPCB Part Number and generate a component using easyeda-converter.

# This will create a component file for you!
npx easyeda convert -i C88224 -o lib/C88224.tsx

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2.2 Create from Scratch with Standard Footprint

If you can’t find the part on JLCPCB, you can create a component from scratch.

There are two parts to creating a component:

1. Find all the pin labels
2. Find out what the footprint looks like
3. Fill in the template

This is what the template for a component looks like:

import { createUseComponent } from "tscircuit"
import type { CommonLayoutProps } from "@tscircuit/props"

const pinLabels = {
  "1": "PWR",
  "2": "DO",
  "3": "GND1",
  "4": "GND2",
  "5": "AO2",
  "6": "AO2",
  "7": "BO2",
  "8": "BO2",
} as const
const pinNames = Object.values(pinLabels)

interface Props extends CommonLayoutProps {
  name: string
}

export const PartName = (props: Props) => {
  return (
    <bug
      {...props}
      footprint="tssop16" // <-- This is the footprint specifier! Find it in the datasheet!
      pinLabels={pinLabels}
      schPinSpacing={0.75}
      schPortArrangement={{
        leftSize: 4,
        rightSize: 4
      }}
    />
  )
}

export const usePartName= createUseComponent(PartName, pinNames)

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2.2.1 Finding the correct footprint

A datasheet will normally include in it’s description somewhere details about the footprint or “landing pattern”. You can paste any package details into text-to-footprint to figure out exactly what footprint string you should use.

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3. Connect your components

Now that you have all the subcomponents, you can connect them together. By importing them into the main MyCircuit.tsx file.

Start by just importing a single component like this:

import { useC88224 } from "gen/C88224"

export const MyCircuit = () => {
  const U1 = useC88224("U1")

  return (
    <group>
      <U1 />
    </group>
  )
}

Now start to connect components together…

import { useC88224 } from "gen/C88224"
import { useCapacitor } from "tscircuit"

export const MyCircuit = () => {
  const U1 = useC88224("U1")
  const C1 = useCapacitor("C1", {
    capacitance: "1uF",
    footprint: "0603",
  })

  return (
    <group>
      <U1 />
    </group>
  )
}

Finally when you’re ready, put it all together by adding every component:

import { layout, useResistor, useCapacitor, useBug } from "tscircuit"
import { TB6612, useTB6612 } from "./TB6612"
import { C88224 } from "gen/C88224"

export const MyCircuit = () => {
  const R1 = useResistor("R1", {
    resistance: "10k", // TODO
    footprint: "res0402",
    schX: -5,
    schY: 0,
  })
  const U1 = useTB6612("U1")
  const C2 = useCapacitor("C2", {
    capacitance: "1uF", // TODO
    footprint: "cap0603",
    schX: -4,
    schY: 1,
  })
  const C3 = useCapacitor("C3", {
    capacitance: "1uF", // TODO
    footprint: "cap0603",
    schX: -6,
    schY: -2,
  })


  return (
    <group>
      <U1
        VM1="net.VMOTOR"
        VM2="net.VMOTOR"
        VM3="net.VMOTOR"
        GND="net.GND"
        AIN1="net.AIN1"
        AIN2="net.AIN2"
        PWMA="net.PWMA"
        AOUT2_1={JP3.MA2}
        AOUT2_2={U1.AOUT2_1}
      />
      <R1 schRotation="90deg" right={U1.VCC} left={U1.STBY} />
      <C2 schRotation="-90deg" left={U1.VCC} right="net.GND" />
      <C3 schRotation="-90deg" left="net.VMOTOR" right="net.GND" />
      <C88224 name="U2" schX={-2} schY={-2} />
    </group>
  )
}