LK204-7T-1U Keypad Question
Posted: Mon Jul 26, 2010 8:43 am
Hello,
I am looking at using the LK204-7T (Non-USB) for one of my projects. I am using a microcontroller that provides dead simple 0-5V TTL for I/O which I understand will work with your LCD by swapping the resistors on the back from RS232 to TTL. However after reading the section describing the keypad I saw no mention of the TTL interface. Is this because the keypad is only supported via RS232 / I2C? If so I would much prefer to use some form of TTL to RS232 conversion circuit, which raises another question. In the documentation it states:
"The LK204-7T-1U provides a DB-9 Connector to readily interface with serial devices which use the EIA232 standard signal levels of +/-30V."
I don't believe I follow. I didn't think +/- 30V was within the defined spec for RS232 / EIA232. Typical ranges being between +/-5V to +/-15V. Admittedly I am a noobie to circuit design and electrical engineering in general but if you could shed some light on this or even just point me in the direction of some decent reading materials I would be much obliged.
Regards,
-B
I am looking at using the LK204-7T (Non-USB) for one of my projects. I am using a microcontroller that provides dead simple 0-5V TTL for I/O which I understand will work with your LCD by swapping the resistors on the back from RS232 to TTL. However after reading the section describing the keypad I saw no mention of the TTL interface. Is this because the keypad is only supported via RS232 / I2C? If so I would much prefer to use some form of TTL to RS232 conversion circuit, which raises another question. In the documentation it states:
"The LK204-7T-1U provides a DB-9 Connector to readily interface with serial devices which use the EIA232 standard signal levels of +/-30V."
I don't believe I follow. I didn't think +/- 30V was within the defined spec for RS232 / EIA232. Typical ranges being between +/-5V to +/-15V. Admittedly I am a noobie to circuit design and electrical engineering in general but if you could shed some light on this or even just point me in the direction of some decent reading materials I would be much obliged.
Regards,
-B