OK, Christian ... first of all, thanks for your valuable input. If
I understand it correctly, only 4 pins (2,3,4,5) of standard DB-9 are used to
build an equivalent DS9097 circuit for 1-wire chips, of which DTR (pin 4)
connects to 1-wire Data (probably DQ for Maxim 1-wire chip), and RXD (pin 2)
connects to 1-wire GND (probably P- for Maxim 1-wire chip). So, with those
diodes and resistors in the picture (protection circuit for the 1-wire chip),
I\'ve decided to build my own little circuit for 4-pin for my board (and not
using off-the-shelf 9-pin DS9097). Conceptually it should work (help me if
I am missing anything): DTR (of DB9) is equivalent to Vcc (my board), RX and TX
(of DB9) are equivalent to TX and RX (my board), respectively, and GND to GND,
of course with an equivalent protection circuit, as shown in the
picture. With this (1-wire chip with my own circuit for 4-pin serial
above, which I presume will be equivalent to DS9097), I guess owfs
would be able to see and mount the /dev/ttyS0, and would NOT complain:
\"Could not detect DS9097\". Any input from you will be useful before I
jump into it. Another question: what about the other pins of DB9 as shown
in the picture? Are they left open, especially handshaking pins like RTS/CTS
(pin 7/8)? Thanks.----On Wed, 12 Sep 2007 20:16:55 +0200
owfs-developers@lists.sourceforge.net wrote
Shouldn’t you be able to use Maxim’s reference design of a passive
9097 adapter? DTR is there to supply 1-wire bus with power since it’s
high when serial-port is opened. This could be replaced with Vcc I think.
Perhaps an extra 100ohm (just after Vcc) to protect it from short-circuit
would be good too. The DTR pin is probably short-protected on all
serial-interfaces, but Vcc on your board is probably not…
Look at the drawing at: http://owfs.sourceforge.net/adapters.html#Serial
Picture: http://owfs.sourceforge.net/adapters/adapter.gif
/Christian From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of suman sarkar Sent: den 12 september
2007 01:59 To: owfs-developers@lists.sourceforge.net Subject:
[Owfs-developers] Re :Re: Re :Re: MIPS vs MIPSEL in OWFS
Hi Christian, Here are some clarifications re: Meraki AP\'s
serial interface. This interface is NOT a regular 9-pin interface
(DB9) as you see in WRT54G. It has only 4 pins: Vcc, Tx, Rx, and GND.
OWFS can only support DS9097 serial adapter, I presume, which has a
regular 9-pin serial configuration. So, any Maxim sensor
chip (which is DS2781K in our case), with DS9097 serial adapter CAN NOT be
directly fed to the AP\'s 4-pin interface. It needs some tweaking, I guess.
Any sugges
tion regarding how to make it compatible with a 4-pin interface?
Thanks.
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