Burning Code in a DIY Arduino

Xenobius:
Hey thanks for your replies.
Yes I know MOSI and MISO goes berserk when programming so I set them up as inputs with buttons to be safe.

Can I use the USBtinyISP with Arduino IDE?

Thanks for the tutorial too :smiley:
X

What is the function of the button and what do you mean Mosi miso goes berserk?
Thanks

I presume he means that he uses those pins as input buttons (for whatever their purpose is). You wouldn't press them during programming.

... goes berserk ...

Has activity on them.

Right... I was refering to a situation I had once where I had a relay connected to MOSI and during programming, the relay kept clicking like mad. Hence were I got the berserk adjective. The buttons are normal push to make buttons which do not have to be pressed during programming. It is understood that by doing so, I would be interfering with the programming but this is better than having a relay or some output connected to them and during programming you would be risking damaging or controlling something.

So, is that means it is better not to connect any input/output device at the MOSI, MISO and SCK pins ? Are you programming using USBasp/usbtiny right ? If you are using ftdi programmer, then it will only involve Tx and Rx

Thanks

True, but then you have to make sure you don't have anything connected to Tx/Rx for best results.

So, is that means it is better not to connect any input/output device at the MOSI, MISO and SCK pins ?

It depends on the device a bit. SPI devices are designed for this sort of thing, you just don't activate them through their slave select pin.

I still dont get for the explanation on SPI pins

Thanks alot ! Great websites you have there !

So do this means that I cant connect anything to this 2 pins ? Or it is not adisable to connect anything here?

It depends what you are doing. On the Uno the Tx/Rx pins are connected to the USB chip and have pull-ups on them, making them not particularly useful as input pins.

Also if you put a load on them you may not be able to upload a new sketch until you disconnect it. This may or may not bother you.

You mention it has pull ups. So meaning that I can put a button there as an input ?

Correct me if I am wrong :slight_smile:

A button to ground should work. Are these just a lot of hypothetical questions or do we have a project here?

Yea, a button to GND and to TX/RX pins should just make it a pull up button right ? So, I think I no need this below code to activate the pull up ?

digitalWrite(0/1, HIGH)

I am just asking for my own notes so I will becareful when in my project :smiley:

Let's not get bogged down here. Possibly that line could be omitted, but if you make a stand-alone version (without the USB chip) then you would need it.

Thanks alot ! :smiley:

Yes this only makes sense when using USBtinyISP.
I need to learn more on SPI... Actually I have difficulty making a distinction from

UART - This is a Tx -> Rx & Rx -> Tx single device connection right?
I2C - As for as I know, this is a 2 wire protocol which can accept a maximum of 255 channels and any device connected to the same channel gets the message sent
SPI - As for SPI, I will try to see the link but so far I have no clue ! :slight_smile:

Cheers

I am too asking questions to learn. I do have a small project (a 16 relay board with 2 pots connected to ADC and 4 buttons) and am trying to design the board from scratch without the usb connection and without the usb-to-serial-ftd-chip.

Xenobius:
I2C - As for as I know, this is a 2 wire protocol which can accept a maximum of 255 channels and any device connected to the same channel gets the message sent

No. Better read this:

Vincent19:
So, is that means it is better not to connect any input/output device at the MOSI, MISO and SCK pins ?

You can safely use them for push buttons and similar inputs that don't mind being driven by the programmer, and for non-critical outputs such as the Data and RS inputs of a text-mode LCD display (the LCD ignores what you put on Data and RS until you pulse EN).