DBOP noise on C200v2 goes away if we precharge long enough.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27148 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 5 insertions, 40 deletions

diff --git a/firmware/target/arm/as3525/dbop-as3525.c b/firmware/target/arm/as3525/dbop-as3525.c
index 87bc46e145..1816b5205b 100644
--- a/firmware/target/arm/as3525/dbop-as3525.c
+++ b/firmware/target/arm/as3525/dbop-as3525.c
@@ -34,49 +34,9 @@
 /* doesn't work with the new ams sansas so far and is not needed */
 static short int dbop_input_value = 0;
 
-#if defined(SANSA_C200V2)
-/*
- * workaround DBOP noise issue cause it's really annoying if your
- * buttons don't work in the debug menu...
- */
-static short int input_value_tmp[2];
-int dbop_denoise_reject = 0;
-int dbop_denoise_accept = 0;
-#endif
-
 /* read the DBOP data pins */
-#if defined(SANSA_C200V2)
-unsigned short dbop_read_input_once(void);
-
 unsigned short dbop_read_input(void)
 {
-    int i;
-
-    while (1) {
-        for (i=0; i<2; i++) {
-            input_value_tmp[i] = dbop_read_input_once();
-        }
-        /* noise rejection */
-        if (input_value_tmp[0] == input_value_tmp[1]) {
-            dbop_denoise_accept++;
-            break;
-        } else {
-            dbop_denoise_reject++;
-        }
-    }
-    if (dbop_denoise_accept + dbop_denoise_reject > 1000) {
-        dbop_denoise_accept /= 2;
-        dbop_denoise_reject /= 2;
-    }
-
-    return dbop_input_value;
-}
-
-unsigned short dbop_read_input_once(void)
-#else
-unsigned short dbop_read_input(void)
-#endif
-{
     unsigned int dbop_ctrl_old = DBOP_CTRL;
     unsigned int dbop_timpol23_old = DBOP_TIMPOL_23;
 
@@ -92,6 +52,11 @@ unsigned short dbop_read_input(void)
                 (1 << 16) |         /* enw=1 (enable write) */
                 (1 << 12);          /* ow=1 (16-bit data width) */
     DBOP_DOUT = DBOP_PRECHARGE;
+#if defined(SANSA_C200V2)
+    /* two additional writes to precharge longer get rid of the read noise */
+    DBOP_DOUT = DBOP_PRECHARGE;
+    DBOP_DOUT = DBOP_PRECHARGE;
+#endif
     while ((DBOP_STAT & (1<<10)) == 0);
 
 #if defined(SANSA_FUZE) || defined(SANSA_E200V2)