modbus: make modbus_poll return value

[openparking.git] / firmware / modbus.h

diff --git a/firmware/modbus.h b/firmware/modbus.h
index 9f5afa6f7329d0c9971cbcb215bbc55500b5b025..e762b706a5173542f795e15eb8cdd16674d21eb8 100644 (file)
--- a/firmware/modbus.h
+++ b/firmware/modbus.h
@@ -8,8 +8,17 @@
  * All bugs by Jan "Yenya" Kasprzak <kas@fi.muni.cz> :-)
  */
 
+/*
+ * Call this at the beginning of the program.
+ */
 void modbus_init(uint8_t unit_id);
-void modbus_poll();
+
+/*
+ * Call this frequently. Returns 0 when no data was received
+ * and the processing went on quickly. Returns 1 after potentially lengthy
+ * packet processing.
+ */
+uint8_t modbus_poll();
 
 typedef enum {
        MB_OK = 0,