I have a little question about using the RESET pin as an i/o pin. I have read somewhere that it can be used as a “weak” i/o pin, not exactly knowing what weak means. So I just tried to flash an LED with it. It works, but REALLY “weakly”. I was just wondering if the reset pin is really that weak or if I can set something to make it brighter w/o using any additional external components.
Which microcontroller are you referring to? Are you using the microcontroller by itself or is it part of a controller board?
sorry for the incomplete post. I am using an ATtiny45. I am just using the MCU, but no controller board. So there is basically just one button further LEDs on other pins and the power supply.
It’s important you specify which MCU you’re using since different chips have different electrical properties. Initially I assumed you were talking about the ATmega168, which we feature in most of our Orangutan robot controllers, but I could find no mention of weak driving strength on the RESET line. However, the datasheet for the ATtiny45 does mention that the RESET line can only function as a weak I/O. Take a look at note 6 on page 167; this note points you to several figures that show the electrical characteristics of the RESET pin when it’s used as a general-purpose digital I/O.
Out of curiosity, can you still program the MCU as normal after you’ve changed the fuses to turn the RESET line into a digital I/O? I was never sure what would happen since the standard ISP programming process transmits SPI commands while RESET is held low.
thanks for the hint. That explains the weak capability of driving an LED. I am using a MOSFET now to get the LED bright.
The AVR cannot be programmed via ISP when the reset pin is disabled. I know that using a bootloader works and I am pretty sure I have read that high voltage programming can be used, too. However, I cannot find where I read this. I’ll let you know when I find it.