To use an Arduino board as an ISP programmer, simply upload the Arduino IDE example sketch named “ArduinoISP”. Next, connect the SPI pins of the Arduino board to the MCU chip or MCU board to be programmed. Then, you can start using the Arduino board as an ISP programmer.

To illustrate the steps for the procedure, first, I will make an Arduino Nano board into an ISP programmer. Then, I will show how to upload sketches and burn bootloaders to a Digispark ATtiny85 development board.

Step by Step Guide on How to Use Arduino as ISP Programmer

STEP 1 – Connect your Arduino board to your computer’s USB port.

Connect the Arduino board of your choice to your programming computer hosting the Arduino IDE. In the next several steps, we will upload the ArduinoISP sketch to the board to make it an ISP programmer.

STEP 2 – Open your Arduino IDE and open the ArduinoISP sketch.

Open your Arduino IDE. If you are a beginner and you have not yet installed the Arduino IDE, please see How to Install Arduino IDE on Windows 10. On the Main menu, select File/Examples/11.ArduinoISP/ArduinoISP.

You should see the screen shown below after clicking on the ArduinoISP on the Built-in Examples menu.

STEP 3 – Choose the name of your Arduino board from the Board Manager’s list.

Go to Tools/Board/Arduino AVR Boards and select the type of Arduino board you are using. As shown in the screenshot below, I chose Arduino Nano for my Arduino board.

STEP 4 – Set the proper COM serial port for your board.

On the Tools menu, select Port. Then select from the serial ports list the appropriate port for your Arduino board.

STEP 5 – Click the Upload button.

As a final step for uploading the ArduinoISP sketch to the Arduino board, click on the Upload button.

When you see the message “Done uploading”, congratulations!!! You now have a full-pledged ISP programmer.

In the following steps, we are going to show how to use the Arduino board acting as an ISP programmer to:

• Program or upload a sketch to a Digispark ATtiny85 board
• Burn an Optiboot bootloader
• Burn a Micronucleus bootloader

STEP 6 – Connect the ISP programmer (the Arduino board) to the Digispark ATtiny85 development board.

Like in any other ISP programmers, including the popular USBtinyISP and USBasp programmers, we use six (6) terminals of the ISP programmer to connect to the device to be programmed. These terminals are:

• MOSI
• MISO
• SCLK
• RESET
• VCC
• GND

On the Arduino board acting as an ISP programmer, the corresponding terminals are as follow:

• D11 (MOSI) —> MOSI
• D12 (MISO) —> MISO
• D13 (SCLK) —> SCLK
• D10 (SS) —> RESET
• 5V —> VCC
• GND —> GND

Now, based on the foregoing discussion, we can connect the Arduino board to the Digispark ATtiny85 board using the following terminals:

Arduino Board —> Digispark ATtiny85 Board
D11 (MOSI) —> PB0(MOSI)
D12 (MISO) —> PB1(MISO)
D13 (SCLK) —> PB2(SCLK)
D10 (SS) —> PB5(RESET)
5V —> 5V
GND —> GND

For reference purposes, the Digispark ATtiny85 development board pinout is shown below. For more information on Digispark ATtiny85, you may consult the Digispark ATtiny85 Pinout and Configuration.

Shown below is the Fritzing breadboard diagram for connecting the Arduino Nano board to the Digispark ATtiny85 board.

How to connect the Arduino Nano board to the Digispark ATtiny85 board illustrated by an old-school schematic diagram.

After connecting the Arduino board to the Digispark ATtiny85 board, we are now ready to test drive the Arduino board as an ISP programmer.

Since we are going to work with the Digispark ATtiny85 board, you must have the board core ATTinyCore by Spence Konde installed on your Arduino IDE. If you do not have the ATTinyCore installed yet, see the article How to Install ATTinyCore on Arduino IDE.

STEP 7 – Copy and Paste the Blink Program.

Going back to the Arduino IDE, create a new sketch and then copy and paste the Blink program sketch shown below.

/*
www.cyberblogspot.com
07Jan2022  
*/

#define LED_BUILTIN 1  //PB1 for Model A
                       //PB0 for Model B

void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

STEP 8 – Change the board from Arduino board to Digispark ATtiny85 board.

Go to Tools/Board/ATTinyCore and select ATtiny25/45/85 (No bootloader). Take note that we are using the “No bootloader” option and NOT the “Micronucleus/Digispark” option. This is because we are going to upload the Blink sketch via an ISP programmer (the Arduino board) and not thru the Digispark’s USB port.

STEP 9 – Select the proper COM port.

Go to Tools/Port and choose the correct COM port from the ports list.

STEP 10 – Select the programmer type.

On the Tools/Programmer menu, select Arduino as ISP as the programmer type.

STEP 11 – Upload the Blink program.

Upload the Blink program by clicking on the Upload button.

When you see the message saying that the upload is done, your Digispark ATtiny85 board should start blinking the built-in LED.

How to Burn Bootloader on Digispark ATtiny85 Using Arduino as ISP Programmer

Burn Optiboot Bootloader

STEP 1 – Select ATtiny45/85 (Optiboot) from the ATtinyCore list.

STEP 2 – Verify that the proper COM port is selected.

STEP 3 – Make sure that the programmer selected is “Arduino as ISP”.

STEP 4 – Click “Burn bootloader” to start the burning process.

Burn Micronucleus Bootloader

To burn the Micronucleus bootloader onto the Digispark ATtiny85 board using the Arduino as ISP programmer, follow the steps above for burning the Optiboot bootloader. However, instead of selecting ATtiny45/85 (Optiboot), select ATtiny85 (Micronucleus / Digispark) from the ATtinyCore list of supported devices.

References on How to Use Arduino as ISP Programmer

In-System Programming (ISP)
How to Install ATTinyCore on Arduino IDE
How to Program ATtiny85 with Arduino IDE
Digispark ATtiny85 Pinout and Configuration
How to Program Digispark ATtiny85 Board with Arduino IDE
Digispark USB Device Not Recognized
How to Use AT-09 BLE with Arduino and Smartphone

The post How to Use Arduino as ISP Programmer appeared first on CyberBlogSpot.

• ATtiny1634
• ATtiny2313/4313
• ATtiny24/44/84
• ATtiny441/841
• ATtiny25/45/85
• ATtiny261/461/861
• ATtiny87/167
• ATtiny48/88
• ATTiny43
• ATtiny828

Additionally, the ATTinyCore supports programming via ICSP AVR programmers, Serial (Optiboot), and VUSB (Micronucleus).

1. Install the Arduino IDE

If you don’t have the Arduino IDE (Integrated Development Environment) yet, you can download it here. As of this writing, the latest stable version is 1.8.19.

2. Add the ATTinyCore URL to the Board Manager

Open the Arduino IDE and on the main menu, select Files -> Preferences. In the Additional Boards Manager URLs textbox, type the URL “http://drazzy.com/package_drazzy.com_index.json“, and then press the OK button.

If the textbox already contains additional URLs, press the button on the right side of the textbox. A window will appear where you can type the URL on a new line.

3. Install the Board

On the main menu, select Tools -> Board -> Board Manager.

When the Board Manager window appears, change the board Type from All to Contributed (1). Next, find and select the ATTinyCore board (2). Then, click the Install button (3). And finally, close the Board Manager window by clicking the Close button (4).

Select the Board

From the main menu, open Tools –> Board –> ATTinyCore and then select the appropriate ATtiny board for your microcontroller.

Note that in selecting a board, you will have to choose among No bootloader, Optiboot, and Micronucleus. First, choose No bootloader if you are programming with an AVR programmer. Second, select Optiboot if your ATtiny MCU has been previously burned with an Optiboot bootloader and it is wired as an Optiboot serial device. Finally, select Micronucleus if the MCU has been flushed with a Micronucleus bootloader and connected as a USB device. For more information about these three (3) programming modes, please see How to Program ATtiny85 in Arduino IDE.

The next and final step depends on your chosen programming mode. If you select No bootloader, then you will need to choose a programmer. Open Tools –> Programmer and select the AVR programmer you are going to use. You may also have to specify the Port if your AVR programmer uses the serial port. Although most AVR programmers like the USBasp and USBtinyISP are USB devices and you won’t have to specify the port.

If you choose Optiboot, you need to specify the serial port. Open Tools –> Port and select the port for your ATtiny microcontroller.

Finally, if you choose Micronucleus, you also don’t have to specify the port because Micronucleus uses a virtual USB device.

Now, you’re ready to start programming your ATtiny microcontroller!

References on How to Install ATTinyCore on Arduino IDE

How to Install Arduino IDE on Windows 10
How to Program ATtiny85 with Arduino IDE
Digispark USB Device Not Recognized
ATTinyCore – ATtiny Arduino core by Spence Konde

The post How to Install ATTinyCore on Arduino IDE appeared first on CyberBlogSpot.

In order to use all these programming modes, we need to install the ATTinyCore. It is an Arduino core designed for the ATtiny family of MCUs. Please see How to Install ATTinyCore on Arduino IDE.

If we install the ATTinyCore in the Arduino IDE, we would get the ATTinyCore board menu shown below. Based on the menu, to program an ATtiny85 in Arduino IDE, three (3) options exists. These are the No bootloader, Optiboot, and Micronucleus/DigiSpark.

Program ATtiny85 in Arduino IDE Using an AVR Programmer (No Bootloader)

What is a Bootloader

Actually, the Arduino IDE recognizes an MCU board because of a bootloader. A bootloader is a small software that resides in the flash memory of a microcontroller. Its main function is to detect an incoming program upload. If it sees one, it takes the program and stores it in the flash memory. Otherwise, it runs a previously loaded program, if any exist.

Without a bootloader, the Arduino IDE cannot directly program or upload sketches to an ATtiny85 chip. Or for that matter, any microcontroller at all.

AVR Programmers

Now, in the absence of a bootloader, how do we program or upload sketches to ATtiny85 using the Arduino IDE? We need an AVR programmer. There are many kinds of AVR programmers. We can see the list of AVR programmers supported by ATtinyCore in the Tools -> Programmer menu.

Shown below is a picture of a USBasp ICSP AVR programmer. USBasp is an open-source AVR programmer that you can build by yourself. Or you can buy it cheap on the Internet. It sells for around two dollars ($2) only.

If you don’t have an AVR programmer but you have an Arduino board lying around, you’re good to go. You can use an Arduino board as an AVR programmer. It is one of the options in the ATtinyCore list of programmers – Arduino as ISP. See How to Program ATtiny85 with Arduino.

Wiring the ATtiny85 to an AVR Programmer

Connecting the ATtiny85 to an AVR programmer is straightforward. We connect the six (6) pins of the AVR programmer to the corresponding six (6) pins of the ATtiny85 chip. That is, we connect the following pins:

PROGRAMMER ATTINY85
MOSI (Pin 1) –> MOSI (Pin 5)
MISO (Pin 9) –> MISO (Pin 6)
SCK (Pin 7) –> SCK (Pin 7)
RST (Pin 5) –> RESET (Pin 1)
VCC (Pin 2) –> VCC (Pin 8)
GND (Pin10) –> GND (Pin4)

Uploading Sketch using AVR Programmer

1. Connect the ATtiny85 chip to the AVR programmer as shown in the diagram above.
2. Connect the AVR programmer to the USB port of a computer running the Arduino IDE. You may have to install a device driver for your AVR programmer. If you are using a USBasp programmer like the one shown above, you need to download and run Zadig. This will install the device driver needed by the USBasp programmer.
3. Open the Arduino IDE. On the main menu, open Tools –> Board –> ATtinyCore and select the board ATtiny25/45/85(No bootloader).
4. Next, open Tools –> Programmer and select your AVR programmer. In my case, I would select USBasp(ATTinyCore).
5. Create your sketch or open an existing sketch you want to upload to the ATtiny85 chip. To start uploading, press the Upload button (right arrow icon). Or you may open Sketch on the main menu and select either Upload or Upload Using Programmer.

Burning Bootloaders

Besides uploading sketches, we use the AVR programmer to burn bootloaders. That is, we can upload bootloaders like Optiboot and Micronucleus into an ATtiny85 chip.

How to Burn ATtiny85 Chip with Optiboot Bootloader

1. On the main menu, open Tools –> Board –> ATtinyCore and select the board ATtiny45/85(Optiboot).
2. Next, open Tools –> Programmer and select your AVR programmer.
3. Finally, open Tools and click on the Burn Bootloader.

How to Burn ATtiny85 Chip with Micronucleus Bootloader

1. On the main menu, open Tools –> Board –> ATtinyCore and select the board ATtiny85(Micronucleus/Digispark).
2. Next, open Tools –> Programmer and select your AVR programmer.
3. Finally, open Tools and click on the Burn Bootloader.

Program ATtiny85 in Arduino IDE using Optiboot Bootloader

If you have been programming an Arduino board (Uno, Nano, etc.) using the Arduino IDE, then you have been using the Optiboot bootloader. The Arduino IDE uploads sketches to an Arduino board by communicating with the Optiboot bootloader. The communication is done thru a serial port. That is why before you upload a sketch, you need to select the proper serial port (COM port).

The ATtiny85 chip does not have a serial device. Therefore, to connect it to the PC running the Arduino IDE, we must provide a USB to serial converter. Shown below is an example of a USB serial converter.

Connecting USB Serial Converter to ATtiny85

We need to connect the following terminals:

Serial Converter ATtiny85
DTR –> RESET (Pin 1)
RXD –> MOSI (Pin 5)
TXD –> MISO (Pin 6)
5V –> Vcc (Pin 8)
GND –> GND (Pin 4)

Note that the DTR terminal from the serial converter does not connect directly to the RESET pin of the ATtiny85. It is connected via a 0.1uF ceramic capacitor. Moreover, a 10K-ohm pull-up resistor is connected to the RESET pin of the ATtiny85.

Uploading Sketch Using Optiboot Bootloader

1. Burn or flash the ATtiny85 with Optiboot bootloader. See above topic – How to Burn ATtiny85 Chip with Optiboot Bootloader.
2. Connect the ATtiny85 chip to a USB serial converter as shown in the diagram above.
3. Connect the USB serial converter to a computer running the Arduino IDE. You may have to install a device driver for your USB serial converter.
4. Open the Arduino IDE. On the main menu, open Tools –> Board –> ATtinyCore and select the board ATtiny45/85(Optiboot).
5. Next, open Tools –> Port and select the serial port (COM port) of the serial converter.
6. Create your sketch or open an existing sketch you want to upload to the ATtiny85 chip. To start uploading, press the Upload button (right arrow icon). Or you may open Sketch on the main menu and select Upload.

Program ATtiny85 in Arduino IDE using Micronucleus/Digispark

Micronucleus is a bootloader like the Optiboot bootloader discussed above. However, Micronucleus does not use a serial port (COM port) to communicate with the Arduino IDE. Instead, it uses a virtual USB device. This virtual device is installed on the computer hosting the Arduino IDE. The virtual USB serves as a go-between for Micronucleus and the Arduino IDE.

On the hardware side, an ATtiny85 with a Micronucleus bootloader needs a USB connector. The USB connector allows it connect to the USB port of the computer running the Arduino IDE.

Digispark Development Board

Now comes the Digispark board. It is a small board fitted with an ATtiny85 chip pre-programmed with the Micronucleus bootloader. Also, the board has the required USB connector. And as a bonus, the board includes a 5V voltage regulator, a power indicator LED, and an extra built-in LED on PB2.

For more information on Digispark ATtiny85, please see:
Digispark ATtiny85 Pinout and Configuration
How to Program Digispark ATtiny85 Board with Arduino IDE
Digispark USB Device Not Recognized

Uploading Sketch Using Digispark Boards

1. We need to install the Digispark device driver before the Arduino IDE can recognize it. We can download the Digispark device driver and run the installer. However, we can also use the Zadig software to install the Digispark driver.
2. Open the Arduino IDE. On the main menu, open Tools –> Board –> ATtinyCore and select the board ATtiny85(Micronucleus / DigiSpark). There is no need to select the Port because Digispark does not use the serial COM port.
3. Create a sketch or open an existing sketch to be uploaded
4. Press the Upload button.
5. Wait for a message to plug in the Digispark board. After inserting the board’s USB, the uploading of the sketch will continue.

References on How to Program ATtiny85 with Arduino IDE

How to Install Arduino IDE on Windows 10
How to Install ATTinyCore on Arduino IDE
Digispark USB Device Not Recognized
Digispark ATtiny85 Pinout and Configuration
How to Program Digispark ATtiny85 Board with Arduino IDE
Types of AVR Programmers – by Nick Gammon
USBasp Project – USB Programmer for Atmel AVR Microcontrollers

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