Looking at this USB Hub controller IC, XR22404, page 5. More confused on the second statement, what does it mean to be asserted for a min of 10 us?
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\$\begingroup\$ S = siemens. s = second. \$\endgroup\$– winnyCommented Apr 5, 2018 at 7:54
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\$\begingroup\$ I think that is one of the reasons I was confused. I suspect they made the mistake of using S instead of the traditional s for seconds. \$\endgroup\$– A.S.Commented Apr 5, 2018 at 8:22
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1 Answer
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It means if you want to reset the chip correctly, you can't just assert the reset signal for 5 us, or 7 us, or 9 us. You have to assert it for at least 10 us, or the device might not reset, or might not reset correctly.
answered Apr 5, 2018 at 5:23
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2\$\begingroup\$ Also, just for clarity (the OP may not understand this), it must be held to within the limit range of \$V_\text{LOW}\$ -- which is what "active low" means. "Asserting it" means "active" and in this case "active" means "LOW." \$\endgroup\$– jonkCommented Apr 5, 2018 at 5:35
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\$\begingroup\$ This can be controlled by either a Raspberry PI GPIO pin or a pull-up resistor with a grounding switch correct? When the pin is grounded is when the reset occurs? \$\endgroup\$– A.S.Commented Apr 5, 2018 at 5:36
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\$\begingroup\$ Do the RPi outputs meet the input level requirements of the other chip? (I have no idea if RPi has 3.3 or 5 V I/Os) If they do, you should be able to hook the RPi GPIO directly to this chip. \$\endgroup\$ Commented Apr 5, 2018 at 6:05