From 5d3c3bcb516788473b9c6197496b9424710d13f8 Mon Sep 17 00:00:00 2001
From: bigalex <bigalex@gmx.de>
Date: Fri, 5 Oct 2012 23:11:24 +0200
Subject: [PATCH] better sond measurment, tolerant to static voltage on piezo

---
 firmware/main.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/firmware/main.c b/firmware/main.c
index 1517851..7677eaf 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -44,6 +44,7 @@ void modeswitch_poll(void){
 void do_mode0(void){
  static timer_t mytimer;
  static uint16_t maxval;
+ static uint16_t lastmaxval;
  uint16_t curval;
 
    if (ModeChanged){
@@ -54,10 +55,14 @@ void do_mode0(void){
      maxval=0;
    };
    if(timer_expired(&mytimer)){
-     USART0_put_uint16(maxval);
-     USART0_crlf();
+     if(maxval>lastmaxval){
+       USART0_put_uint16(maxval);
+       USART0_crlf();
+     };
      timer_set(&mytimer, 1);
-     if (maxval>0) {led_on(LED_R|LED_L);} else {led_off(LED_R|LED_L);};
+     if (maxval>lastmaxval) {led_on(LED_R|LED_L);} else {led_off(LED_R|LED_L);};
+
+     lastmaxval=maxval;
      maxval=0;