about updating fromserial only in serial rx isr

diff --git a/detpic/nmra-stream.asm b/detpic/nmra-stream.asm
index a101a765cfeea081bfb3f71ce926585feddbc5e2..7d010362cbddb60fb45a2f82019bfb63b9fc6573 100644 (file)
--- a/detpic/nmra-stream.asm
+++ b/detpic/nmra-stream.asm
@@ -37,7 +37,9 @@ totrackbit    res     1       ; bit location of pointer within byte
  ;
  ; fromserial points to the first empty byte, where we will put new
  ; data provided by the host; this means that (fromserial & 0xf0) is
- ; the first buffer which fails to contain a complete nmra message
+ ; the first buffer which fails to contain a complete nmra message.
+ ; fromserial is updated only by the (low priority) serial receive
+ ; interrupt handler.
  ;
  ; totrack points to the first remaining full byte, which is currently
  ; being transmitted; if nothing is currently being transmitted