Bare-Metal MCU #4 - Bootloaders and Programmers 

@@MitchDavis2 I watched several other techniques for make it alive. But eventually failed, And do you have any idea of making bare metal programming on Interrupt with atmega328p (uno or nano). That was hard to grasp. Think I could use help.

@@MitchDavis2 To be frank that's not a big project. Actually making custom libraries. We do have avr libc though. Idea is to learn a different approach apart from Arduino IDE. I am curious to know about using only datasheet as you did. Once done will let you know!!!. Thanks a lots for those replies on interrupt video that will help me and others. Great work 👍🏻

thank you got it!

@@testme2026 What's the answer to your question? It seems to be gone!

What was the answer?

If I had to guess, Mitch wanted to demonstrate that ICSP uses the SPI protocol to flash the micro, and that you can connect the jumpers directly to the micro instead of the ICSP, although both methods work!

previous to reading data sheet.

Watch at 16:00 again. The connector for programming is shared with the passive LED. He also mentioned that the LED will blink when programming.

Take a peek at my stm32 videos :) You need either a programmer, or make sure there’s a bootloader on the microcontroller that allows you to program it in some other way (such as USB or UART)

I haven’t used a whole lot of TI microcontrollers yet. I’m planning on wrapping up the STM32 series, and then I’ll probably move to PIC or RaspberryPi Pico after that

If you flash the chip using some external device (either a second arduino, or a programmer) it will erase the bootloader by default. You can always add the bootloader back in by going into the arduino IDE and hitting "Tools" →"burn bootloader". Burning the bootloader requires an external programmer as well. Basically, without a bootloader, the arduino doesn't really know how to talk over USB to get a new program.

@@MitchDavis2 Thanks for the reply Mitch!

The USB port doesn’t necessarily have anything to do with a bootloader. A bootloader is mostly just a program that lives on the microcontroller that is able to talk to SOMETHING to get a new program. By default, you can only program over SPI (and parallel i think). With a bootloader, you could program over UART (using less pins than SPI) or something like SD Cards, or even something like ethernet. Basically, any “communication” method could be used to push a new program onto the microcontroller, even if it’s not the native SPI approach If you need the extra space, it’s totally acceptable to go without a bootloader.

@@MitchDavis2 Sorry to bother you again. (Awesome series btw, keen to learn more about C in general now.) Is loading a program using UART more cumbersome than SPI to justify the hassle of adding a boot loader?

@@JakeFace0 There's not really a straight forward answer to this since it's highly situational, so I'll give you some idea about past projects I've done, and how I handled programming. Firstly, I ALWAYS put SPI pins/pads somewhere on the board. That way, if I ever mess something up or corrupt a bootloader, I always have a safety backup method to program the microcontroller or re-flash a bootloader. PROJECT 1: No bootloader One project I worked on would take sensor signals and output them over UART. It was a pretty simple project, so I didn't put much thought into it. It was industrial, so I had to encase the entire circuit board in epoxy. I programmed this over SPI, and didn't use a bootloader. I quickly regretted this design choice because once I epoxied the circuit board, I could no longer re-program it because I didn't have access to the SPI pins. It also sucked to know that I had access to the UART pins (since that's what the data output was) but I couldn't reprogram it over UART because I didn't have a UART bootloader on the chip. Project 2: Bootloader caused problems I made a small personal RFID project which just used an RFID reader to activate selections on a vending machine. The RFID reader I used would send the RFID code over UART, so I hooked that up to the UART pins on an arduino. The only problem is that I could no longer program the arduino over UART (or USB) because the UART pins were being actively used by the RFID reader, which prevented the arduino software from pushing new code onto the chip via UART. I had 2 options to fix this: program the chip over SPI, or add a physical switch that disconnected the RFID's UART pins from the arduino so they wouldn't interfere. I ended up adding a disconnect because I didn't want to have an arduino floating around without a bootloader, which would be asking for future headaches.

It sounds like you either have a bad chip, or it’s wired up incorrectly. “FFFFFF” is all 1’s (1111 1111 1111 1111 1111 1111). This means youre probably not even communicating with the chip. Feel free to send a pic of it if you want a second set of eyes on it

@@MitchDavis2 where to add the pic ? And i tried it with other ics too and all the configuration and wiring like i checked it multiple times, i am using latest arduino ide 1.8.13 on window 10

@@MirAclE-mf2pu I like to upload pictures to Imgur.com and post links. Give that a try

@@MitchDavis2 ohk i will do that, thanks for helping

@@MitchDavis2 photos.app.goo.gl/7P9Z8Mk8pSUqKiEJ8 Here are the pics of my connection and the error i am getting

Absolutely. If you read the datasheet, you can learn how to self-program the flash memory. Then you just need to come up with a way to receive that program and write it into flash memory.

@@MitchDavis2 I was talking to someone about loading os in Arduino like raspberry pi with Kali and he mentioned bootloader and stuff I had to check on, sorry to bother but can Arduino or atmel, at least any, hold say Kali? And thanks for the reply 👍👍👍

@@aspirohk3558 I doubt it can hold an OS like kali. You need quite a bit of Ram and program memory to run Linux. However, there’s something called FreeRTOS (free real-time operating system) that can run on Arduino. It’s super light-weight in terms of operating systems, and it mimics how operating systems work by being able to execute “multiple” programs. The operating system executes each of these programs to simulate multi-threading.

@@MitchDavis2 nice I'll research on that and see how if resources allow....ooooh what about if I add up extra say expansions like external ram and storage....🤔🤔🤔like in a normal motherboard would it manage?

@@aspirohk3558 at that point, you’re basically re-inventing the computer. You have a processor (or microcontroller in this case) at the heart, and then you add external ram, flash/hard drive, etc to make a full computer. Unfortunately, that’s a massive project to take on. You’d have to understand how the Linux kernel expects to access files, and then write drivers to make sure that files make it where they’re supposed to go. Also, I don’t believe Arduino has support for external RAM/flash, which means you’d have to get incredibly creative and virtualize it yourself. The raspberry pi foundation (and beaglebone/orangePi/bananaPi,jetson, etc) have already done this

Mitchel Davis you are correct it does use TTL I do need something though incase I break my boot loader. I have ALOT of attiny85s. looking forward to fuse burning. PLEASE have an eli5 on it lol. Cause I’ve broke a few already.