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

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27148 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Tobias Diedrich 2010-06-27 02:50:24 +00:00
parent ac40959c48
commit eefe273ce6
2 changed files with 5 additions and 51 deletions
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45
firmware/target/arm/as3525/dbop-as3525.c
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@ -34,48 +34,8 @@
/* 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)