diff --git a/firmware/drivers/adc.c b/firmware/drivers/adc.c
index 4c9206e62b..7be9baf5d5 100644
--- a/firmware/drivers/adc.c
+++ b/firmware/drivers/adc.c
@@ -22,38 +22,25 @@
 #include "thread.h"
 #include "adc.h"
 
-/* This driver updates the adcdata[] array by converting one A/D channel
-   group on each system tick. Each group is 4 channels, which means that
-   it takes 2 ticks to convert all 8 channels. */
-
-static int current_group;
+static int current_channel;
 static unsigned short adcdata[NUM_ADC_CHANNELS];
+static unsigned int adcreg[NUM_ADC_CHANNELS] =
+{
+    ADDRAH_ADDR, ADDRBH_ADDR, ADDRCH_ADDR, ADDRDH_ADDR,
+    ADDRAH_ADDR, ADDRBH_ADDR, ADDRCH_ADDR, ADDRDH_ADDR
+};
 
 static void adc_tick(void)
 {
-    /* Copy the data from the previous conversion */
-    if(current_group)
-    {
-        adcdata[4] = ADDRA >> 6;
-        adcdata[5] = ADDRB >> 6;
-        adcdata[6] = ADDRC >> 6;
-        adcdata[7] = ADDRD >> 6;
-    }
-    else
-    {
-        adcdata[0] = ADDRA >> 6;
-        adcdata[1] = ADDRB >> 6;
-        adcdata[2] = ADDRC >> 6;
-        adcdata[3] = ADDRD >> 6;
-    }
+    /* Read the data that has bee converted since the last tick */
+    adcdata[current_channel] =
+    *(unsigned short *)adcreg[current_channel] >> 6;
 
-    /* Start converting the next group */
-    current_group = !current_group;
-    ADCSR = ADCSR_ADST | ADCSR_SCAN | (current_group?4:0) | 3;
-
-    /* The conversion will be ready when we serve the next tick interrupt.
-       No need to check ADCSR for finished conversion since the conversion
-       will be ready long before the next tick. */
+    /* Start a conversion on the next channel */
+    current_channel++;
+    if(current_channel == NUM_ADC_CHANNELS)
+        current_channel = 0;
+    ADCSR = ADCSR_ADST | current_channel;
 }
 
 unsigned short adc_read(int channel)
@@ -61,20 +48,44 @@ unsigned short adc_read(int channel)
     return adcdata[channel];
 }
 
-void adc_init(void)
+/* Batch convert 4 analog channels. If lower is true, convert AN0-AN3, 
+ * otherwise AN4-AN7. 
+ */
+static void adc_batch_convert(bool lower)
 {
-    ADCR  = 0x7f; /* No external trigger; other bits should be 1 according
-                     to the manual... */
+    int reg = lower ? 0 : 4;
+    volatile unsigned short* ANx = ((unsigned short*) ADDRAH_ADDR);
+    int i;
 
-    /* Make sure that there is no conversion running */
+    ADCSR = ADCSR_ADST | ADCSR_SCAN | reg | 3;
+
+    /* Busy wait until conversion is complete. A bit ugly perhaps, but 
+     * we should only need to wait about 4 * 14 µs  */
+    while(!(ADCSR & ADCSR_ADF))
+    {
+    }
+
+    /* Stop scanning */
     ADCSR = 0;
 
-    /* Start with converting group 0 by setting current_group to 1 */
-    current_group = 1;
+    for (i = 0; i < 4; i++)
+    {
+        /* Read converted values */
+        adcdata[reg++] = ANx[i] >> 6;
+    }
+}
+
+void adc_init(void)
+{
+    ADCR  = 0x7f; /* No external trigger; other bits should be 1 according to the manual... */
+
+    current_channel = 0;
+
+    /* Do a first scan to initialize all values */
+    /* AN4 to AN7 */
+    adc_batch_convert(false);
+    /* AN0 to AN3 */
+    adc_batch_convert(true);
     
     tick_add_task(adc_tick);
-
-    /* Wait until both groups have been converted before we continue,
-     so adcdata[] contains valid data */
-    sleep(2);
 }