Meinberg GPS161 - Manual (Page 10)

10
BSL inputs
Whenever the on-board software must be upgraded or modified, the new firmware
can be downloaded to the internal flash memory using the serial port COM0. There is
no need to insert a new EPROM.
The contacts of a key have to be connected to the BSL inputs of GPS161. If this key
is pressed while the power supply of the module is switched on, a bootstrap-loader is
activated and waits for instructions from the serial port COM0. The new firmware can be
sent to GPS161 from any standard PC with serial interface. A loader program will be
shipped together with the file containing the image of the new firmware.
The contents of the program memory will not be modified until the loader program has
sent the command to erase the flash memory. So, if the BSL key is pressed unintentional-
ly, the firmware will not be changed accidentially. After the next power-up, the system
will be ready to operate again.
Installation
Power supply
The module GPS161 has two independent paths for connecting the power supply. The
main supply of +5 V must be connected to the contacts ‘VCC’ of the contact strip (see
pin assignments in ‘Technical specifications GPS161’). The supply for the master
oscillator (‘VDD’, +5V) is seperated from these contacts, because disturbing voltages on
the power lead could decrease the short term stability of the oscillator.
It is possible to use only one +5 V-output of a power supply for connecting the
receiver module and the oscillator. The ‘VCC’ and ‘VDD’ inputs should have seperate
leads from the power supply in this case. The contacts for the reference potential are
connected internaly. To achieve a good EMC-behaviour of GPS161 as much ‘GND’
pins of the contact strip as possible should be connected to the ground potential of the
power supply directly.