Amateur radio, programming, electronics and other musings

Trimble Thunderbolt (RS232)

Trimble Thunderbolt (RS232)

If you are planning to connect your Trimble to a microcontroller as I am you will need to provide it appropriate levels as the RS-232 standard defines the voltage levels that correspond to logical one and logical zero levels for the data transmission and the control signal lines.  Valid signals are plus or minus 3 to 15 volts; the ±3 V range near zero volts is not a valid RS-232 level. The standard specifies a maximum open-circuit voltage of 25 volts: signal levels of ±5 V, ±10 V, ±12 V, and ±15 V are all commonly seen depending on the power supplies available within a device. RS-232 drivers and receivers must be able to withstand indefinite short circuit to ground or to any voltage level up to ±25 volts.

The common way of interfacing RS232 to a processor is via a MAX232.  Don’t forget the MAX232 inverts the signal so you will need to allow for that in your code.

!CB9mcHQ!2k~$(KGrHqUOKo4E0WBDB9G2BNJkROzlWQ~~_12I took the easy way out and purchased a small module from Jungletronics (ebay) designed for this purpose.  Cost a few pounds and is pretty much plug and play (except for making the interface cable to the Netduino.  I also decided to put them back to back so bought a male to male gender changer too.

The Thunderbolt connects to your computer via a 9 pin serial port.  Standard pins are in use.

  1. Not used
  2. Transmit (TxD)
  3. Receive (RxD)
  4. Not used
  5. Ground (Gnd)
  6. Not used
  7. Not used
  8. Not Used
  9. Not Used