From 7a5d4011f56334c05b55bb511c2f1f6a4639c8c1 Mon Sep 17 00:00:00 2001
From: Jens Arnold <amiconn@rockbox.org>
Date: Sun, 15 Apr 2007 23:35:56 +0000
Subject: Moved SH1 ADC to target tree.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13174 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/sh/adc-sh.c | 108 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 firmware/target/sh/adc-sh.c

(limited to 'firmware/target/sh/adc-sh.c')

diff --git a/firmware/target/sh/adc-sh.c b/firmware/target/sh/adc-sh.c
new file mode 100644
index 0000000000..d36624f913
--- /dev/null
+++ b/firmware/target/sh/adc-sh.c
@@ -0,0 +1,108 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2002 by Linus Nielsen Feltzing
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+#include "cpu.h"
+#include "system.h"
+#include "kernel.h"
+#include "thread.h"
+#include "string.h"
+#include "adc.h"
+
+/**************************************************************************
+ ** The A/D conversion is done every tick, in three steps:
+ **
+ ** 1) On the tick interrupt, the conversion of channels 0-3 is started, and
+ **    the A/D interrupt is enabled.
+ **
+ ** 2) After the conversion is done (approx. 256*4 cycles later), an interrupt
+ **    is generated at level 1, which is the same level as the tick interrupt
+ **    itself. This interrupt will be pending until the tick interrupt is
+ **    finished.
+ **    When the A/D interrupt is finally served, it will read the results
+ **    from the first conversion and start the conversion of channels 4-7.
+ **
+ ** 3) When the conversion of channels 4-7 is finished, the interrupt is
+ **    triggered again, and the results are read. This time, no new
+ **    conversion is started, it will be done in the next tick interrupt.
+ **
+ ** Thus, each channel will be updated HZ times per second.
+ **
+ *************************************************************************/
+
+static int current_channel;
+static unsigned short adcdata[NUM_ADC_CHANNELS];
+
+static void adc_tick(void)
+{
+    /* Start a conversion of channel group 0. This will trigger an interrupt,
+       and the interrupt handler will take care of group 1. */
+
+    current_channel = 0;
+    ADCSR = ADCSR_ADST | ADCSR_ADIE | ADCSR_SCAN | 3;
+}
+
+void ADITI(void) __attribute__((interrupt_handler));
+void ADITI(void)
+{
+    if(ADCSR & ADCSR_ADF)
+    {
+        ADCSR = 0;
+
+        if(current_channel == 0)
+        {
+            adcdata[0] = ADDRA >> 6;
+            adcdata[1] = ADDRB >> 6;
+            adcdata[2] = ADDRC >> 6;
+            adcdata[3] = ADDRD >> 6;
+            current_channel = 4;
+            
+            /* Convert the next group */
+            ADCSR = ADCSR_ADST | ADCSR_ADIE | ADCSR_SCAN | 7;
+        }
+        else
+        {
+            adcdata[4] = ADDRA >> 6;
+            adcdata[5] = ADDRB >> 6;
+            adcdata[6] = ADDRC >> 6;
+            adcdata[7] = ADDRD >> 6;
+        }
+    }
+}
+
+unsigned short adc_read(int channel)
+{
+    return adcdata[channel];
+}
+
+void adc_init(void)
+{
+    ADCR  = 0x7f; /* No external trigger; other bits should be 1 according
+                     to the manual... */
+
+    ADCSR = 0;
+    
+    current_channel = 0;
+
+    /* Enable the A/D IRQ on level 1 */
+    IPRE = (IPRE & 0xf0ff) | 0x0100;
+    
+    tick_add_task(adc_tick);
+    
+    sleep(2);    /* Ensure valid readings when adc_init returns */
+}
-- 
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