avr32dd20-devkit: use unimplemented "CH" pin as a boost bypass control

For 3V LEDs on a boost/buck dual fuel driver, this allows
routing power around the boost converter in li-ion mode,
to reduce resistance and increase maximum output.
The AA/NiMH mode is unaffected, and boosts as normal.

1 files changed, 13 insertions, 0 deletions

diff --git a/hw/thefreeman/avr32dd20-devkit/hwdef.c b/hw/thefreeman/avr32dd20-devkit/hwdef.c
index 3e5dd79..460082f 100644
--- a/hw/thefreeman/avr32dd20-devkit/hwdef.c
+++ b/hw/thefreeman/avr32dd20-devkit/hwdef.c
@@ -30,6 +30,11 @@ void set_level_zero() {
     delay_4ms(IN_NFET_DELAY_TIME/4);
     IN_NFET_ENABLE_PORT &= ~(1 << IN_NFET_ENABLE_PIN);
 
+    #ifdef USE_BST_BYPASS
+    // turn off bypass
+    BST_BYPASS_PORT |= (1 << BST_BYPASS_PIN);
+    #endif
+
     // turn off boost last
     BST_ENABLE_PORT &= ~(1 << BST_ENABLE_PIN);  // BST off
 }
@@ -48,6 +53,14 @@ void set_level_main(uint8_t level) {
     // BST on first, to give it a few extra microseconds to spin up
     BST_ENABLE_PORT |= (1 << BST_ENABLE_PIN);
 
+    #ifdef USE_BST_BYPASS
+    // turn on bypass in li-ion mode
+    if (voltage > DUAL_VOLTAGE_FLOOR)
+        BST_BYPASS_PORT &= ~(1 << BST_BYPASS_PIN);  // low = bypass
+    else  // turn off bypass in AA/NiMH mode
+        BST_BYPASS_PORT |= (1 << BST_BYPASS_PIN);  // high = boost
+    #endif
+
     // pre-load ramp data so it can be assigned faster later
     // DAC level register is left-aligned
     PWM1_DATATYPE dac_lvl  = PWM1_GET(level) << 6;