From: Jake Bordens (newton_at_allaboutjake.com)
Date: Wed Sep 21 2005 - 05:46:59 PDT
I've found an inconsistency in the N2 developer documentation on
UNNA. <http://www.unna.org/unna/apple/documentation/n2platform>
The "Internal Serial Slot Developers Guide" lists pin one as "Port
select" and says:
"The control signal to select between a peripeheral in the inernal
serial slot and the Newton Interconnect Port. When the signal is
LOW, the Interconnect port may drive Serial 3. When HIGH the
Internal Slot may drive Serial 3"
So LOW = External Port, HIGH = Internal Port. All seems well except
I can't for the life of me figure out how to get this pin to toggle.
None of the GPIO's toggle it as far as I can tell.
Next up is the "Newton Interconnect Designer's Guide"
Here we find that:
"If serial 3 is to be used on the EXTERNAL port, the software needs
to disable the use of the internal slot. To do this the signal
InternalModemSelect needs to be driven HIGH."
So, LOW=Internal, HIGH = External
Which is it? :) My guess is that the signals not being named the
same (PortSel vs InternalModemSelect) is a good indicator that the
documentation isn't the highest quality.
My trusty ocilloscope tells me that this pin is usually LOW. And
since the Interconnect Designer's Guide also says, "The newton OS is
configured to enable the serial port to the INTERNAL slot as
default." leads me to believe that it might be the right one.
Any thoughts from those in-the-know?
I'm planning in v1.1 of my Internal Bluetooth module to move it to
Port 3. If anyone's interested in why I'll be glad to tell you, but
for now, this message is long enough.
Take care,
Jake
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