add short info about debug uart

diff --git a/trb3/AdditionalModules.tex b/trb3/AdditionalModules.tex
index c7c8a8b862fead6dbb20d0971eb5c71651e5b8eb..da7f6c60d6f843e690d51ffedb4d70cd5fe9af33 100644 (file)
--- a/trb3/AdditionalModules.tex
+++ b/trb3/AdditionalModules.tex
@@ -127,7 +127,10 @@ means ``end of file''. In 32 bit mode, 2 more padding bytes are added in order t
 16 bit mode 4 data words can be stored, and in 32 bit mode 2 data words. The data words are always stored in big-endian.
 
 
-
+\subsection{Debug Interface}
+If included in the design, two pins of the boards are used as a UART interface at 115.2 kbaud 8N1. Perl scripts can use this interface
+instead of the normal HADES::TrbNet by including daqtools/perllibs/TrbNetUart.pm. With manual access the syntax is \verb!Raaaa! or \verb!Waaaavvvvvvvv!, 
+where aaaa is the register address and vvvvvvvv is the value to be written, both in hexadecimal numbers.