Can I use Serial1 and OneWire at the same time on STEP?

STEP and STEP+ (not STEP.IR) add RS232 level translators for TINI's serial1 UART. TINI also uses this UART through the DS2480 (installed on the TINI module) for TINI's "external" OneWire net access. The STEP schematics page 7, show the details. Here is a cropped section of that page. JP4 is a jumper which controls how serial1 can be used, see the table below:
JP4 controls serial1 use as RS232 or OneWire
JP4 in position 1-2: P5.7 (PCE3(L)) controls serial1. P5.7 High selects OneWire, Low selects RS232. High after a reset or startup, which enables OneWire (this is the default for Dallas eXX socket boards.) Your program can drive P5.7 low to enable RS232. Use TINI's Bitport class to drive P5.7.
JP4 in position 2-3: DS2480 is disabled, this disables OneWire and makes serial1 RS232. In this position P5.7 has no effect.

Note that serial1 is in an "either-or" mode - either TINI's DS2480 is enabled for OneWire access OR the RS232 level shifter is enabled for RS232 access. The ability to use P5.7 as a switch between the modes means that your program can switch between OneWire and RS232 on serial1 as you wish. Of course, you can't be sending or receiving data on each connection at the same time. If you are using serial1 as OneWire, then any incoming RS232 data will be missed.

Can I use Serial1 with CMOS (not RS232) levels to my own device in the STEP prototype area?

This is a little bit tricky. In order to do this, you need to disable TINI's DS2480 OneWire adapter by driving the EN2480 signal low. You can do this by installing JP4 in the 2-3 position. However this enables the RS232 level shifter for serial1. You can unsolder and remove U5, the RS232 level shifter, or just lift the leg of U5 which drives the signal XRX1, the serial1 CMOS level receive. This is U5-13. Then you can connect your CMOS-level device to TX1 and XRX1. Your TX1 signal will still be output through U5 onto the serial1 DB9, but this will cause no harm if nothing is connected to it.


Is the OneWire modular connector on STEP compatible with the Blue Dot Reader, etc?

Yes, STEP's RJ12 (technically an RJ11 connector with 6 conductors used is called an RJ12). Here's the pinout:

STEP and Dallas eXX RJ11 pinout
Looking into the RJ11/12 socket with the key on the bottom,
pin 1 is on your left.
 1  VCC (5V regulated)
 2  ground
 3  One Wire Data
 4  One Wire Return (usually connected to ground pin 2)
 5  not connected
 6  VRAW (unregulated 6-12V or more from socket board or 1-Wire net)

The blue dot readers and Dallas 9097X only use the center 2 conductors, OneWire Data and Return. So they can be plugged directly into STEP's OneWire RJ receptacle.