Hello,
For our upcoming project we have confirmed MiFi is working well with LTE Telus Network in Canada, and are looking forward to moving ahead with our custom product design based around MiFi, very exciting!
We will be powering the unit externally through the 5V/Gnd terminals added in V2.5 hardware (thanks!), and adding connections to the GPIO pins on the right side of the PCB (J4). A few questions about using those pins:
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The first 3 pins are Identified as 5V, 3.3v and Gnd. Can you let me know current rating for those? Specifically, is the 5V current limited in any way, or is simply a pass through from the main 5V rail of the power supply. (Specifically, if I need to draw 200-300mA can I pull from that pin, or do I need to split off from my external 5V power supply directly?)
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The AR9331 Datasheet identifies that some GPIOs act as special “hardware controls” during initial power on of the chip. Specifically, GPIO #0 is listed as:
“SEL_25M_40M - Indicates the frequency of the external clock. Power detection on GPIO0.”
For our project this PIN will be tied to an external source and used to track as an input. So to avoid issues, I need to know if Default state of the pin should be 0 (low = 25M external clock), or 1 (high = 40M external clock), or if external clock is not in use and state of this pin doesn’t matter.
We ran into this issue during testing when we found out that GPIO1 is the hardware control for boot sequence, and that pulling it low tells the chip to boot from internal ROM instead of SPI flash! So now we always pull high to be safe ;o) Just want to know if we need to do the same for GPIO0, or if needs to be pulled low instead…
Thanks!
-Rob