Terastation Serial console

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Revision as of 19:02, 19 April 2005 by WikiSysop (Talk)

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As we can see from the hardware page, the CPU offers two serial ports. The first one is used for the system console, but it's not accessable from outside the box. The seccond one is used to communicate with the XXX microcontroller.

But if we recheck the specs there is support for an UPS with serial port. And there actually is a serial port on the back of the box.

If we open the box, there is the serial port in lower back corner:

Serial port orig.jpg

Close to it is a Sipex3220EE level shifter to convert the 5v (or 3.3v) TTL-levels to RS232.

If we look closely the three, actually four, pins of the level shifter are connected to middle pin of the three connectors: JP3 (Tx), JP4 (Rx), JP5 (Vcc).

Inorder to connect the system console we must first remove the three 0-ohm resistor (R437, R440, R441) and move them to (R438, R439, R442).

Removing the SMD resistors already is a pain, so I decided to add three pin-heads/jumper.

[[Image:]]

Unforunately this does not yet work. We also have to bridge R76 to get input from the serial port to the CPU. Do 'not' remove R75, it is a 10k-ohm pull-down. If you remove it the input to the CPU will float and feed random junk to it, not what you want.

J1 can be used to direclty access the serial console, but it's uses 3.3v TTL levels and you need a seperate level shifter. I added some connectors, as I've a proper level shifter from some oher embedded projects.