TTL/CMOS

[hani_a]

Hello,

I had several fast questions regarding serial communications:
A) is the signal level dependent on the chip i'm programming or the board i'm using to program the chip?
B) Are there any other signal levels other than ttl/cmos/rs232 used for microcontrollers?
C) how does one find out the signal level output by a board/chip?

i appreciate the help,

hani a.

 

[Nigel Goodwin]

Hello,

I had several fast questions regarding serial communications:
A) is the signal level dependent on the chip i'm programming or the board i'm using to program the chip?

Both or either.

B) Are there any other signal levels other than ttl/cmos/rs232 used for microcontrollers?

There can be, I've been using a PIC16LF628 off 3V today, actually two AA batteries.

C) how does one find out the signal level output by a board/chip?

Measure it, or consult the datasheets.

You would probably be better off asking specific questions, your existing ones are really too vague.

 

[hani_a]

hello again and thanks for the reply,

I'll be a little more specific; i'm programming an analog device that requires a ttl signal for communication. i'm also using an stk500 board and an atmega16 chip. i tried to transmit a char via the uart port and was wondering if the output signal is ttl/cmos/rs232.. i simply don't know. i've looked at the datasheets of the stk500 and the atmega16 but they dont mention anything about ttl or cmos or rs232. any suggestions?

hani a.

 

[Russlk]

My giving you advice is like the blind leading the blind, but in 40 years I have picked up some tidbits of information. The atmega16 has 32 I/O ports and operaties on +5 volts. RS232 is out because it uses + and - voltage. The only difference between TTL and CMOS is the impedance level. The data sheet (143 pages) will tell you the source and sink capability of the outputs and the voltage and current requirements of the inputs.

 

[TillEulenspiegel]

My giving you advice is like the blind leading the blind, but in 40 years I have picked up some tidbits of information. The atmega16 has 32 I/O ports and operaties on +5 volts. RS232 is out because it uses + and - voltage. The only difference between TTL and CMOS is the impedance level. The data sheet (143 pages) will tell you the source and sink capability of the outputs and the voltage and current requirements of the inputs.

Not quite. Rs-232 voltages are +- 12 V , TTL voltages are ground and +5VDC.
The output of the Amtel device ( since the supply is +5VDC ) is limited to that range unless you use either a TTL to CMOS level converter or a TTL input CMOS output level output UART. The TTL signal is used for short range communications, typically < a few meter or so. The 232 is a very old convention, there are new better schema's. I don't know what Your trying for as usual the better the description, the easier to find a solution.

 

[weegee]

My giving you advice is like the blind leading the blind, but in 40 years I have picked up some tidbits of information. The atmega16 has 32 I/O ports and operaties on +5 volts. RS232 is out because it uses + and - voltage. The only difference between TTL and CMOS is the impedance level. The data sheet (143 pages) will tell you the source and sink capability of the outputs and the voltage and current requirements of the inputs.

Not quite. Rs-232 voltages are +- 12 V , TTL voltages are ground and +5VDC.
The output of the Amtel device ( since the supply is +5VDC ) is limited to that range unless you use either a TTL to CMOS level converter or a TTL input CMOS output level output UART. The TTL signal is used for short range communications, typically < a few meter or so. The 232 is a very old convention, there are new better schema's. I don't know what Your trying for as usual the better the description, the easier to find a solution.

Most devices also respond to INVERTED TTL, as an RS232 Signal, thus a lot of devices dont require the MAX232 or similar to convert to RS232 Levels. INVERTED TTL is now VERY common on serial devices.

Just my 2 Cents

 

[TillEulenspiegel]

True weegee, but again the range is limited..the max 232 is exactly what I had in mind tho......