The Autohelm Seatalk databus to interface between different instruments in yachting equipment is famous but no official standard. Because of this the only accessories you can use are Autohelm's own, which are quite expensive sometimes.
I am working on a small unit that was primarily intended as a remote control unit for the auto pilots with Seatalk interface. Any unit that can use the Autohelm Z101 remote control unit should be able to use my unit as well. However, the project increased in size, and now also includes a LCD display that works as a repeater that can display auto pilot information, depth, speed, course, wind speed, wind angle, water temperature and current LAT/LON position. It also includes a small NMEA output interface that sends some basic information from the Seatalk bus in NMEA sentences. The unit can also include a IR receiver module, which will allow you to send steering commands over wireless IR link from an ordinary 3rd party remote control unit.
If you want to order this unit, please use the order form. Note that I make these units as a hobby project and that the mechanical finish of the work is accordingly. If you are good at mechanical work (making the display hole in the box and holes for the buttons) and want to try to make it yourself, please tell me to not put it in the box for you...
I have also written a simple chart plotting software that can talk to this unit and understand the Seatalk information and extract and display most instrument information and position. This software can understand both NMEA and Seatalk, but use the Seatalk information from this unit for more complete information (as the NMEA port have a limited number of sentences).
Here is a small picture of what my finished unit looks like. There are 5 push buttons on the top, 2 red to the left (-10 and -1), 1 white in the middle (info) and 2 green to the right (+1 and +10). Left of the display you can see the IR receiver as a small dot. Note that the repeater display show the same value as the Autohelm unit. Where am I now???
The different information screens that can be displayed (selected by the white button in the middle) looks like this:
PILOT xxx´ Auto
Autopilot info
xxxxxxx|XXXXXXX
Speed Depth Comp Speed,
Depth and course info
xx.xk xx.xm xxx´
Wind Angle Temp
Wind and water temp info
xxms xxx´R xx.x´
GPS 012"59.60' N GPS position
info
045"59.99' E
The NMEA sentences that will be transmitted are: VHW (course/speeed), VWR (wind info), DBT (depth), GLL (position info) and MTW (water temp).
The unit is using a PIC 16F84. This microcontroller is quite suitable, except the program memory is a little bit too small. Because of this, some features that I would like to add, are missing.
For those of you that want to build this unit, I can offer different alternatives.
1. Programmed PIC controller and PCB (mounting board), SEK 250
(US$ 25).
2 Programmed PIC, PCB and all necessary components in a
DIY kit, SEK 500 (US$ 50).
3. A ready built unit, SEK 900 (US$ 90).
This includes air mail shipping worl wide.
We prefer cash in the mail or bank transfer, but also accept all major credit cards. If you are interested in the project and want to be on our mailing list or if you want to order something, please mail to mikael@ridax.se
I have now added the capability to "remote control the remote control" from an ordinary Sony TV remote control. This means that the Autohelm remote control can include a IR receiver module (cost US$ 2) that allows it to understand commands from an ordinary Sony TV remote control. There are plenty of 3rd party remote control units that emulate the Sony remote control commands, and I have found one specially suited one for this purpose that have almost only the buttons I use, arranged in a logical way for my purpose (this unit cost US$ 10). Unfortunately, the PIC processor memory can not hold all the program, so there are now two compilation versions of the software, one with IR remote control capability that leaves out the VHW, VWR and DBT sentences from the NMEA interface, and one version that does not have IR capability. If you have the IR PIC version, you must also mount a IR receiver unit (or an extra pull-up resistor replacing the IR receiver, if you want the IR PIC without IR receiver for some reason). Here is a picture of the remote I found, that I think is suitable (from swedish company Clas Ohlson part no 32-5297).
Here is a PCB layout for the mounting board, so you can decide if you want to build the unit yourself or get a ready unit (the real size is around 4*3 cm):
Here is a component list:
| 16F84 | PIC 16F84 controller |
| C_5V | 220uF capacitor |
| C_OSC1 | 22pF capacitor |
| C_OSC2 | 22pF capacitor |
| DISPLAY | 2*16 LCD display, 14/16 (backlit) pin interface |
| OSC1 | 4 Mhz oscillator |
| R_LED | 350 Ohm, 1/2 W |
| R_NMEA | 200 Ohm, 1/4 W |
| R_PULLUP | 1 kOhm, 1/4 W |
| R_ST_IN | 510 kOhm, 1/4 W |
| R_ST_OUT | 200 Ohm, 1/4 W |
| T_ST_IN | BC547 |
| T_ST_OUT | BC639 |
| V_REG | 7805, at least 0.5 A, TO220 |
Here is a picture of a ready built PCB unit (not so sharp though):
Here you can download the building description in english
or svenska