SX52 info

Rsadeika

Two questions:
1.A description for Port A states "symmetrical drive". Can someone, in lay terms, explain what that refers to, and how it is used.

2.Is their a way of adding or accessing more data memory. This would be within the context of the SX proto board. The docs state 262x8, I guess to some, salvation would be in order. But since their is a 5 bit addressing scheme, have I answered my own question.

Thanks
PS please save the sarcasm for someone else.

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pjv

Hi There;

Symmetrical drive means the transistors in the port can "push" (source current) equally well as they can "pull" (sink current).

As far as data memory is concerned; not directly, but certainly via software, either parallel (uses lots of I/O pins) or serial (uses many fewer I/O pins).

Cheers,

Peter (pjv)

Rsadeika

Peter, thanks for answering the questions without a brow beating. Could you answer two more?
1.Hi-Z input or output, is this like turbo mode(lol)?

2.TTL and CMOS, ·which would be preference.

Thanks.

Jon Williams

1. Hi-Z (high impedance) in when the pin is set to an input state; when made an output there is a low-impedance path to Vdd (high) or Vss (low).

2. That depends on where you want the transition to occur. When timing the discharge of a cap, for example, TTL is preferable as the transition is at 1.4 volts so there is a greater "distance" between 5 (fully charged) and 1.4 (transition to 0). If the pin was set to CMOS and running at 5 volts, the transition point would be 2.5 volts. Given the same cap timing routine, the granularity would be greater.

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Jon Williams
Applications Engineer, Parallax

pjv

Well no, they are totally different issues.

Turbo refers to the mode the SX is operating in; that is downward compatible with some (1655??) PIC's reduced feature set. Hi-Z refers to an output's being temporarily disconnected so it neither sinks or sources. Inputs are always (relatively) Hi-Z.

TTL/CMOS depends somewat on your application. In the many years I have been programming the SX, I have never yet used TTL. I like the concept of the processor switching at half of Vcc. It allows me to play a lot of analog tricks with the SX.

Cheers,

Peter (pjv)

Guenther Daubach

TURBO Mode ???

When I bought a PC software product many years ago, it came together with a bumper sticker reading "I feel the need for speed" - fortunately not too many German cops understand English .

Using an SX comes close to driving a racing car, so why should you throttle it down?

Therefore, each of your assembly programs (for SXes below 48) should contain those two directives:

DEVICE TURBO
DEVICE OPTIONX

to make use of their full power (not necessary for the "larger" 48/52 devices - they are racing cars by default).

Happy SX-ing,

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Greetings from Germany,

G