Hello all,
I've got two devices which communicate through a serial interface (one with an actual rs232 port and the other a 4 pole minijack). I would like to know whether I can hook them up to each other without causing any damage due to incompatible voltage levels (or something else). However, I have a hard time interpreting the information I've got. I hope someone here can help me with this.
What I know of the first device is the following (receiving data):
- "The output is open drain, the input is 5 volt tolerant."
- "The normal level is 5v. Its output is open drain with a weak pullup to 5v."
From the second device I know the following (sending data):
- It uses the MAX3243 driver (http://www.ti.com/product/max3243).
- I can access its serial output at two different levels:
-- "RS232 levels using a MAX3243 driver, the datasheet says RS232 levels at min 5V, typ 5.4V"
-- "COM2 is also available at 3.3V CMOS levels"
One observation:
- Open drain seems to be related to Mosfets, so I guess also CMOS
Questions:
- What does "min 5V, typ 5.4V" mean? That its signal is minimal ±5v but typical (or on average) ±5.4v. Which could mean that possibly it is sometimes well above the ±5.4v and thus too high for the receiving device.
- Assuming the first device can recognize ±3.3v as a valid 1 or 0 (I think most serial devices operating at ±5v do), could I connect the ±3.3v to the bus of the first device (without causing damage)?
I hope I have made my problem clear and that someone has some answers for me, because this is out of my league and I wouldn't like to damage my equipment.
Thanks in advance, Maarten
I've got two devices which communicate through a serial interface (one with an actual rs232 port and the other a 4 pole minijack). I would like to know whether I can hook them up to each other without causing any damage due to incompatible voltage levels (or something else). However, I have a hard time interpreting the information I've got. I hope someone here can help me with this.
What I know of the first device is the following (receiving data):
- "The output is open drain, the input is 5 volt tolerant."
- "The normal level is 5v. Its output is open drain with a weak pullup to 5v."
From the second device I know the following (sending data):
- It uses the MAX3243 driver (http://www.ti.com/product/max3243).
- I can access its serial output at two different levels:
-- "RS232 levels using a MAX3243 driver, the datasheet says RS232 levels at min 5V, typ 5.4V"
-- "COM2 is also available at 3.3V CMOS levels"
One observation:
- Open drain seems to be related to Mosfets, so I guess also CMOS
Questions:
- What does "min 5V, typ 5.4V" mean? That its signal is minimal ±5v but typical (or on average) ±5.4v. Which could mean that possibly it is sometimes well above the ±5.4v and thus too high for the receiving device.
- Assuming the first device can recognize ±3.3v as a valid 1 or 0 (I think most serial devices operating at ±5v do), could I connect the ±3.3v to the bus of the first device (without causing damage)?
I hope I have made my problem clear and that someone has some answers for me, because this is out of my league and I wouldn't like to damage my equipment.
Thanks in advance, Maarten