SparkFun Forums

[masterdisaster]

Hi,

Just received my isp500-tiny. I work on a mac. I first started Parallels, then AVRstudio, connected my isp500-tiny to the macbook. AVRstudio connects to isp500-tiny, no problem. Can read out the chip-id. And also program the chip.

But does the isp500 also have power enough to feed my complete circuit? It seems not, because the LCD in my circuit doesn't work. Or does the isp500 not supply +5 on the ISP pins but 3.3v?

Do I always need an external power supply for my circuit because the usb-power is limited? Or is the isp500 already limited for current-consumption?

My solution would be, disconnect the +5v (pin 2) on the ISP connector on my project, connect the GND on the ISP connector to my project along with all miso/mosi/reset etc.
And then connect an external +5v supply to my project. (so iow, not using the pin2 from the isp500-tiny)
Am I right, or should the isp500-tiny deliver enough current to smallscale projects?

[Liencouer]

Looks like the isp500 is not meant to power your target through the programming header. See the caveat on page 9 of AVR-ISP500-TINY User Manual.

CAVEAT: Although the programmer will happily accept setting VTARGET and ARef in the “HW SETTINGS” tab, these actions will have no effect. The programmer hardware can only read target VCC and show it simultaneously in the VTARGET and ARef sliders.

Therefore I think you should power your target as you normally would, and leave the VTarget pin connected on the ISP header.