I can't seem to find any data on the value of the "weak" pull-ups on the IO pins during configuration if the HSWAPEN pin is configured to give them. Does anyone know approximately what value the pull is? I need to counter it for some logic - needs pulling down during configuration.
Also, I'm confused about the direction of the HSWAPEN pin - one set of documentation says pull down to enable pullups, but another implies pull down to disable pullups. Which is correct?
-- Thanks in advance. Nobby Anderson
HSWAPEN is the Input Dedicated pin. Active High input used to disable weak pre-configuration I/O pull-up resistors: 0 = weak pre-configuration I/O pull-up resistors enabled 1 = weak pre-configuration I/O pull-up resistors disabled HSWAPEN must be connected to either enable or disable the pull-up.
This is depends on your custo design, if you want to disable/enable the function.
Regards, Sachin resistors. HSWPEN has a weak pull-up prior to and during configuration.
HSWAPEN is the Input Dedicated pin.
Active High input used to disable weak pre-configuration I/O pull-up resistors:
0 = weak pre-configuration I/O pull-up resistors enabled1 = weak pre-configuration I/O pull-up resistors disabled HSWAPEN must be connected to either enable or disable the pull-up resistors.
HSWPEN has a weak pull-up prior to and during configuration.
This is depends on your custom design, if you want to disable/enable the function.
This means your all I/O pins would be pulled-up to VCCIO voltages during configuration. If you don't want to pulled-up ur all I/O's to Pulled-up to VCCIO then you can disable it.
Regards,
Sachin
Thanks for clarifying the direction of the pin. Do you have any idea of the strength of the weak pullups? In most cases I want the pullup, but for a couple IO pins I want to override it with a stronger pulldown in the preconfigurationn time. If no one knows I guess I'll just have to suck it and see, but I'm surprised there doesn't seem to be any indication what "weak" means in the docs.
Cheers, Nobby
-- Nobby Anderson
Nobby,
The weak pullup is specified here:
page 3 of 5.
From 40uA to 200 uA depending on Vcco.
200 uA @ 3.3 volts, 40 uA at 1.5 volts.So if VccoConfig=2.5v, that is 120 uA. 2.5/120uA =~ 21 K ohms R min.
All of those are max values.
Min is 5 uA for any Vcco.
2.5/5 uA = 500 K ohms. Max R pullup.Austin
Ah, I misunderstood that, I was looking for a different "weak" and "normal" or "strong" value, or some such. I guess they really mean that if there's a pullup, they're always week, and this is the value. The documentation could be a little clearer, and not use the term "weak" in some places and not in others.
Thanks for that, Austin, that's sorted me out.
Cheers, Nobby
-- Nobby Anderson
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