Am Sonntag, 12.09.04 um 12:47 Uhr schrieb Arnd-Hendrik Mathias:
Hi Peter,
in fact the circuit plan is only half of the truth because it is a
generic schematic. It only figures out the logical level regardless of
the concrete example. The documentation states the plan to communicate
witha PC-RS232 interface. This doesn't only mean inverting the logical
level of the signal but furthermore converting the low TTL signal -
which might be about 3V (?) high while not transmitting anything, 0V
for the start bit and again 3V (? usually depends on HW) for any 1 set
Bit and Stop Bit - to the logical inverted +-12V signal of a RS232
interface (self explanatory you cannot expect this level from a max.
3.3V powered MSP ;°). Possible Hardware you could use is stated in the
section "Demonstration Circuit" in slaa078a.pdf or any other standard
RS232 converter (e.g. MAXIM, etc....).
Hope this helps a little bit. Have much fun
Arnd-Hendrik
Hi Arnd-Henrik,
I already have an adapter that converts RS232 levels to levels which
can be used from the MSP. What I want to get rid is the inverter in the
application note. At the moment the signal coming from the MSP is low
active, but what I need is a high active signal from the capture
compare unit ...
As I wrote playing with the ccr settings was not successful so far.
Peter
