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linux-automation / usbsdmux

USB-SD-Mux Project - Driver and Documentation
GNU Lesser General Public License v2.1
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Current drive?? #81

Open akomakul opened 3 weeks ago

akomakul commented 3 weeks ago

Hi, Could you please let me know how much current would drive the below pin in the image?

image

SmithChart commented 3 weeks ago

The pin is driven low by an SN74LVC1G07 and Pulled high by a 10k resistor. According to the datasheet the SN74LVC1G07 can sink up to 32mA.

What do you want to drive using this signal? Maybe we can find a better solution on the board.

akomakul commented 3 weeks ago

Thanks for the reply.

Our device has 2 modes, flashing mode to update software via SD card and normal mode boots via eMMC. We are connecting SD card to PC to write new image and then connect to DUT. After connecting to DUT we want to switch to flashing mode. For doing this we want to control the pin on the device using an extra GPIO pin on USB-SD-Mux but as such option is not available and as you have explained in https://github.com/linux-automation/usbsdmux/issues/49 we want to use the above mentioned pin.

SmithChart commented 3 weeks ago

OK, that sounds reasonable. Driving some logic level pin should be OK for this net. (As long as the open drain output + Pull-Up to 3.3V works for your DUT.)