[NTLK] MP2x00 Internal Interconnect Breakout

Matthias Melcher mm at matthiasm.com
Mon Jan 5 08:00:30 EST 2015

> On Jan 5, 2015, at 10:11 AM, Matthias Melcher <mm at matthiasm.com> wrote:
>> On Jan 5, 2015, at 2:37 AM, Jake Bordens <jake at allaboutjake.com> wrote:
>> He has code to toggle the DIO pin for Serial 3.   What's interesting to me 
>> is that the ROM actually has two functions already:
>> 0x0026d050	SerialPort0LineDriverConfig__16TVoyagerPlatformFUcT1	
>> 0x0026d094	SerialPort3LineDriverConfig__16TVoyagerPlatformFUcT1	
> Seems like I have to dive into the ROM ;-)

Sorry for the following total mess of information. Let me know if I should elaborate on any of this. 

OK, some more technical information from "back then":

Serial Port 0 uses gpSerPortSel on pin 8. When gpSerPortSel switches high, the card must respond with a low on DCD (5).

TVoyagerPlatform::SerialPort0LineDriverConfig(unsigned char, unsigned char) writes to GPIO6 which is gpSerPortSel.

TVoyagerPlatform::PowerOnSubsystem(unsigned long) calls this function, but the value for gpSerPortSel is already inside the TVoyagerPlatform class.

The same is true for TVoyagerPlatform::PowerOffSubsystem(unsigned long)

but I can't find the code that would test any of the serial ports pins.

Aaah, here's a snippet I found in my docs:

Internal Modem connector

Port 0 (serial)

Pin	Name	Dir	LTC1323
2	TDX		I	4	TXD		TXD+-
4	RTS		I	6	/TXDEN	
5	DCD		O	9	/RXO	/RXI
6	CTS		O	10	RXO		RXI
7	RXD		O	11	RXD0	RXD+-
8	gpSerSel	I	7	SHDN	H -> shutdown chip

PortSel goes low, stays low if

Last annotation: SER 001 uses a LTC1323 and a hand full of caps (EMI Filters), but no other active parts.

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