AN-6131API
13
Holt Integrated Circuits
RT Mode using external BC
Using an external BC tester (such as Ballard USB 1553) to transmit messages to the demo
board.
1.
When an external BC is connected using conventional 1553 buses, use cables to connect the
demo board circular tri-axial bus jacks to bus coupler ports on the A and B bus networks. In this
case any external bus load 70 Ω resistors should be disconnected.
If bus couplers are not readily available, bench testing can be done by connecting external
dummy bus load 70 Ω resistors and connecting BC tester cables directly to the demo board tri-
axial jacks for buses A and B.
2.
Press the RESET button and then Press ‘B’ to enable the RT (RT1) then Press ‘K’ and ‘T’ to
activate the RT traffic on the console. Compose a BC to RT message with SA=1 and 32 data
words similar to the message shown below using external BC tester equipment.
3.
The console should show the message transmitted by the BC, after the transaction.
4.
When transmitting repeating messages at a high rate typical of MIL-STD 1553, the RT Traffic
shown on the console may not keep pace due to limitations of the console 115,200 baud rate
and the prolific use of slow-to-execute
printf
function calls in the C program’s console user
interface. Depending on the message content and repetition rate, some messages may not show
on the console. All messages are transacted properly and captured by enabled RT and MT, some
messages simply will not be shown on the console.
