Page 230 - Hacking Roomba

Chapter 11 — Connecting Roomba to the Internet 211

Creating Your Own SitePlayer Telnet Roomba Adapter

The SitePlayer Telnet box is very nice, but somewhat expensive. And if you don’t need true
RS-232 but instead need 0-5V TTL serial (like with the Roomba), it’s wasteful. Figure 11-5
shows a schematic based on the box design, but simplified. The circuit consists of really just
the SitePlayer Telnet module, the RJ-45 jack, a voltage regulator, and a Mini-DIN 8-pin cable.
The RJ-45 jack needs a few resistors and capacitors to help filter out any noise picked up on
the Ethernet cable, and that’s about it.

RJ-45
U1
1
1
2 2 1 LINK* LSENSE* 18
3 3 R2 2 TPIN+ LED 17
4 4 3 TPIN- SP_CTS 16
5 5 100 4 TPOUT- SP_DTR 15
R1
6 6 5 TPOUT+ SP_RTS 14
7 7 100 6 GND SP_DSR 13
8 8 7 RXD SP_DCD 12
8 11
LF1S022 9 TXD SP_RI 10
VCC RESET
C2 VCC 8 mini-din 8pin
C4 SITEPLAYER TELNET MODULE GND 7
C1 0.01µF C3 0.01µF TXD 6 5
0.01µF 0.01µF RXD 4 3
2
+16VDC 1
GND X1
VCC
IN OUT
C5 GND C6
U2 LED1
1µF 7805 1µF
R3 220

GND GND
FIGURE 11-5: Schematic for homemade SitePlayer Telnet Roomba adapter

Figure 11-6 shows the constructed circuit. Construction of it is very similar to the serial tether,
and all the same techniques and tools used for the serial tether should be used here.The SitePlayer
Telnet module is attached by way of female header modules like those used for the Bluetooth
module in Chapter 4.