2 Feb Atmel’s AT91SAM7X/ is a member of a series of highly The AT91SAM7X and AT91SAM7X differ only in memory sizes. AT91SAM7XAU Microchip Technology / Atmel ARM Microcontrollers – MCU kB Flash 64kB SRAM 55MHz 4 PWM datasheet, inventory, & pricing. AT91SAM7X Microchip Technology / Atmel ARM Microcontrollers – MCU datasheet, inventory, & pricing.

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Simple cheap and compact. Protecting the IoT with Invisible Keys. Sign in Sign in Remember me Forgot username or password? I ended up using a hand full of Transistors to cover these issues properly.

Atmel AT91SAM7X256

The pullups are enabled on reset and are possibly powerfull enough to supply enough current through the ULN Welcome to the club. Of course if you want the default state to be off so it doesn’t drive the relays, then you either need to use a pair of transistors or use a PNP transistor on the high side instead of an Wt91sam7x256 on the low.


Embedded Software Engineer Loft Orbital’s mission is to make space simple for organizations that need I didn’t find an errata in the Atmel datasheet.

Arduino Robotics Lonnie Honeycutt. A very minor nit. It turns on both FETs and can create problems. My problem is that I get a high impulse at power at91sma7x256 of about 25ms, which is enough for the relais to switch.

AT91SAM | GPIO problem with AT91SAM7X

So a 1 kohm pull-down should do the trick. I’m used that GPIO come up with high impendancy and this behavour is really unexpected. BTW, the English is relays. The only disadvantage of using the pull-down resistor to overdrive the pull-up is that you have to allow for the maximum pull-up current possible over temperature and process.

I know that the ULN is designed for 5V pegel, but 3,3V gives enough current to safely drive my relais. But then if you are running the relays at a higher voltage than the CPU, this won’t work either.


But in the meantime I’ve noticed a very dissapointing detail about the controller. This pulse is a flat 3,3V signal, no power up glitches or something. Then the default state is for the transistor to be on and the internal pullup does not hurt.

Create free account Forgot password? That’s what inverters are for. It seems that I need external pulldown to compensate them Introduction to Microcontrollers Mike Silva.

On Thu, At91sam7s256 16, at Therefor use extra transistors – they do inverting for you for proper PowerUp. I don’t see any code piece in the startup code tampering with the GPIO. I was going to ask what your drive configuration was. Looks like your PA inputs can source as much as uA of current.