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diff --git a/_site/archive/arduino-uno/index.html b/_site/archive/arduino-uno/index.html index 7509267..3b0234d 100644 --- a/_site/archive/arduino-uno/index.html +++ b/_site/archive/arduino-uno/index.html @@ -2,12 +2,12 @@ <html> <head> <meta charset="utf-8"> - <title>Programming ATmega328P chips</title> + <title>ATmega328P chips</title> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> - <title>Programming ATmega328P chips</title> + <title>ATmega328P chips</title> <link rel="stylesheet" href="/assets/css/main.css"> <link rel="stylesheet" href="/assets/css/skeleton.css"> </head> @@ -40,15 +40,15 @@ <main> <div class="container"> - <h2 class="center" id="title">PROGRAMMING ATMEGA328P CHIPS</h2> + <h2 class="center" id="title">ATMEGA328P CHIPS</h2> <h6 class="center">10 APRIL 2025</h5> <br> - <div class="twocol justify"><p>This post is a step-by-step guide for wiring up ATmega328P ICs to run at 5V -with a 16MHz crystal and 3.3V with an 8MHz crystal. While the 5V -configuration is common, the 3.3V configuration can be advantageous in -low-power applications and when interfacing with parts that run at 3.3V.</p> - -<h2 id="5v-16mhz-configuration">5V-16MHz configuration</h2> + <div class="twocol justify"><p>This is a quick reference for wiring up ATmega328P ICs to run at 5V and 3.3V. +While the 5V configuration is common, the 3.3V configuration can be useful in +low-power applications and when interfacing with parts that themselves run at +3.3V. In this guide, the 5V setup is configured with a 16MHz crystal +oscillator, while the 3.3V configuration makes use of an 8MHz crystal +oscillator.</p> <p>The steps that follow refer to the following pinout.</p> @@ -65,6 +65,8 @@ low-power applications and when interfacing with parts that run at 3.3V.</p> </tr> </table> +<h2 id="5v-16mhz-configuration">5V-16MHz configuration</h2> + <ol> <li>Connect pin 1 to 5V via a 10kΩ resistor.</li> <li>Connect a 16MHz crystal oscillator across pins 9 and 10.</li> @@ -73,23 +75,30 @@ low-power applications and when interfacing with parts that run at 3.3V.</p> <li>Connect pins 8 and 22 to ground.</li> </ol> -<p>In addition to the connections described above, it’s a good idea to add 0.1μF +<p>In addition to the the connections above, it’s a good idea to add 0.1μF decoupling capacitors between pins 7, 20, and 21 and ground. <a href="Makefile">Here’s</a> a sample Makefile for avr-gcc and avrdude.</p> <h2 id="33v-8mhz-configuration">3.3V-8MHz configuration</h2> -<p>The following steps use Arduino Uno as an ISP and Arduino utilities to program -ATmega328P’s bootloader and the fuses (e.g., BOD level) for a 3.3V supply.</p> +<p>Standard ATmega328P chips are preconfigured to run at 5V. To run one at 3.3V, +we must first modify its fuses (e.g., BOD level). If the chip contains a +pre-installed bootloader that expects a 16MHz clock (such as the Arduino Uno +bootloader), it must be replaced with one that is more amenable to an 8MHz +clock.</p> + +<p>In the following steps, we use an Arduino Uno as an in-system programmer to +replace the embedded bootloader and modify the appropriate fuses.</p> <ol> - <li>Upload the ‘ArduinoISP’ sketch to the Uno.</li> - <li>Wire up the ATmega328P as described in the previous section. Replace the 5V -supply with a 3.3V supply and use an 8MHz crystal instead of the 16MHz + <li>Upload the ‘ArduinoISP’ sketch to the Arduino Uno.</li> + <li>Wire up the ATmega328P IC as described in the previous section, while +replacing the 5V supply with a 3.3V supply and 16MHz crystal with an 8MHz crystal.</li> <li>Connect the SPI ports (SCK, MISO, and MOSI) of the two MCUs.</li> - <li>Connect Uno’s SS pin to the IC’s pin 1 (RESET).</li> - <li>The IC can be powered by the Arduino Uno’s 5V pin.</li> + <li>Connect the Arduino Uno’s SS pin to the IC’s RESET pin (pin 1).</li> + <li>Connect the IC’s V<sub>CC</sub> to a 5V supply (e.g., the Arduino Uno’s 5V +pin).</li> <li>Burn the bootloader to the ATmega328P: <ul> <li>Select ‘ATmega328P (3.3V, 8MHz)’ from Tools > Processor.</li> @@ -100,14 +109,14 @@ crystal.</li> </ol> <p>The ATmega328P is now ready to run at 8MHz with a 3.3V power supply. You can -upload programs to the ATmega328P as you usually would using avrdude. +upload programs to the ATmega328P as you normally would using avrdude. <a href="3v3.Makefile">Here’s</a> a sample Makefile with adjusted parameters (e.g., baud rate) for an 8MHz clock.</p> <p>In both configurations, if you intend to use the ATmega328P’s analog-to-digital converter with the internal 1.1V or AV<sub>cc</sub> voltage as reference, do -not connect AREF (pin 21) to V<sub>cc</sub>. Refer to section 23.5.2 ADC -Voltage Reference in the datasheet for more information.</p> +not connect AREF (pin 21) to V<sub>cc</sub>. Refer to section 23.5.2 in the +datasheet for more information.</p> </div> <p class="post-author right">by Wickramage Don Sadeep Madurange</p> |