diff --git a/board/build.mk b/board/build.mk
index 9d9bd57b..43b54eea 100644
--- a/board/build.mk
+++ b/board/build.mk
@@ -33,6 +33,11 @@ dfu:
 	$(DFU_UTIL) -a 0 -s 0x08004000 -D obj/$(PROJ_NAME).bin
 	$(DFU_UTIL) --reset-stm32 -a 0 -s 0x08000000
 
+dfu_recover:
+	$(DFU_UTIL) -a 0 -s 0x08000000 -D obj/bootstub.$(PROJ_NAME).bin
+	$(DFU_UTIL) -a 0 -s 0x08004000 -D obj/$(PROJ_NAME).bin
+	$(DFU_UTIL) --reset-stm32 -a 0 -s 0x08000000
+
 bootstub: obj/bootstub.$(PROJ_NAME).bin
 	./tools/enter_download_mode.py
 	$(DFU_UTIL) -a 0 -s 0x08000000 -D obj/bootstub.$(PROJ_NAME).bin
@@ -62,7 +67,7 @@ endif
 obj/cert.h: ../crypto/getcertheader.py
 	../crypto/getcertheader.py ../certs/debug.pub ../certs/release.pub > $@
 
-obj/%.$(PROJ_NAME).o: %.c obj/cert.h obj/gitversion.h
+obj/%.$(PROJ_NAME).o: %.c obj/cert.h obj/gitversion.h config.h
 	$(CC) $(CFLAGS) -o $@ -c $<
 
 obj/%.$(PROJ_NAME).o: ../crypto/%.c
@@ -71,13 +76,13 @@ obj/%.$(PROJ_NAME).o: ../crypto/%.c
 obj/$(STARTUP_FILE).o: $(STARTUP_FILE).s
 	$(CC) $(CFLAGS) -o $@ -c $<
 
-obj/$(PROJ_NAME).bin: obj/$(STARTUP_FILE).o obj/main.$(PROJ_NAME).o obj/early.$(PROJ_NAME).o
+obj/$(PROJ_NAME).bin: obj/$(STARTUP_FILE).o obj/main.$(PROJ_NAME).o obj/early.$(PROJ_NAME).o obj/llgpio.$(PROJ_NAME).o
   # hack
 	$(CC) -Wl,--section-start,.isr_vector=0x8004000 $(CFLAGS) -o obj/$(PROJ_NAME).elf $^
 	$(OBJCOPY) -v -O binary obj/$(PROJ_NAME).elf obj/code.bin
 	SETLEN=1 ../crypto/sign.py obj/code.bin $@ $(CERT)
 
-obj/bootstub.$(PROJ_NAME).bin: obj/$(STARTUP_FILE).o obj/bootstub.$(PROJ_NAME).o obj/sha.$(PROJ_NAME).o obj/rsa.$(PROJ_NAME).o obj/early.$(PROJ_NAME).o
+obj/bootstub.$(PROJ_NAME).bin: obj/$(STARTUP_FILE).o obj/bootstub.$(PROJ_NAME).o obj/sha.$(PROJ_NAME).o obj/rsa.$(PROJ_NAME).o obj/early.$(PROJ_NAME).o obj/llgpio.$(PROJ_NAME).o
 	$(CC) $(CFLAGS) -o obj/bootstub.$(PROJ_NAME).elf $^
 	$(OBJCOPY) -v -O binary obj/bootstub.$(PROJ_NAME).elf $@
 
diff --git a/board/can.h b/board/can.h
index f2d08ad8..f8387db1 100644
--- a/board/can.h
+++ b/board/can.h
@@ -99,4 +99,3 @@ int can_cksum(uint8_t *dat, int len, int addr, int idx) {
   s = 8-s;
   return s&0xF;
 }
-
diff --git a/board/config.h b/board/config.h
new file mode 100644
index 00000000..d9304bd8
--- /dev/null
+++ b/board/config.h
@@ -0,0 +1,23 @@
+#ifndef PANDA_CONFIG_H
+#define PANDA_CONFIG_H
+
+//#define DEBUG
+//#define DEBUG_USB
+//#define CAN_LOOPBACK_MODE
+
+#ifdef STM32F4
+  #define PANDA
+  #include "stm32f4xx.h"
+#else
+  #include "stm32f2xx.h"
+#endif
+
+#ifdef PANDA
+  #define ENABLE_CURRENT_SENSOR
+  #define ENABLE_SPI
+#endif
+
+#define USB_VID 0xbbaa
+#define USB_PID 0xddcc
+
+#endif
diff --git a/board/early.c b/board/early.c
index de1e3602..bac6c6be 100644
--- a/board/early.c
+++ b/board/early.c
@@ -1,14 +1,10 @@
-#ifdef STM32F4
-  #define PANDA
-  #include "stm32f4xx.h"
-#else
-  #include "stm32f2xx.h"
-#endif
-
+#include "config.h"
 #include "early.h"
+#include "llgpio.h"
 
 int has_external_debug_serial = 0;
 int is_giant_panda = 0;
+int revision = PANDA_REV_AB;
 void *g_pfnVectors;
 
 // must call again from main because BSS is zeroed
@@ -19,12 +15,28 @@ void detect() {
   for (i=0;i<PULL_EFFECTIVE_DELAY;i++);
   has_external_debug_serial = (GPIOA->IDR & (1 << 3)) == (1 << 3);
 
-  // detect is_giant_panda
-  is_giant_panda = 0;
 #ifdef PANDA
-  GPIOB->PUPDR |= GPIO_PUPDR_PUPDR1_1;
+  // detect is_giant_panda
+  set_gpio_pullup(GPIOB, 1, PULL_DOWN);
   for (i=0;i<PULL_EFFECTIVE_DELAY;i++);
-  is_giant_panda = (GPIOB->IDR & (1 << 1)) == (1 << 1);
+  is_giant_panda = get_gpio_input(GPIOB, 1);
+
+  // detect panda REV C.
+  // A13 floats in REV AB. In REV C, A13 is pulled up to 5V with a 10K
+  // resistor and attached to the USB power control chip CTRL
+  // line. Pulling A13 down with an internal 50k resistor in REV C
+  // will produce a voltage divider that results in a high logic
+  // level. Checking if this pin reads high with a pull down should
+  // differentiate REV AB from C.
+  set_gpio_mode(GPIOA, 13, MODE_INPUT);
+  set_gpio_pullup(GPIOA, 13, PULL_DOWN);
+  for (i=0;i<PULL_EFFECTIVE_DELAY;i++);
+  if(get_gpio_input(GPIOA, 13))
+    revision = PANDA_REV_C;
+
+  // RESET pull up/down
+  set_gpio_pullup(GPIOA, 13, PULL_NONE);
+
 #endif
 }
 
diff --git a/board/early.h b/board/early.h
index d1bdff4a..26608cf5 100644
--- a/board/early.h
+++ b/board/early.h
@@ -2,11 +2,15 @@
 #define POST_BOOTLOADER_MAGIC 0xdeadb111
 #define PULL_EFFECTIVE_DELAY 10
 
+#define PANDA_REV_AB 0
+#define PANDA_REV_C 1
+
 extern uint32_t enter_bootloader_mode;
 extern void *_app_start[];
 extern void *g_pfnVectors;
 extern int has_external_debug_serial;
 extern int is_giant_panda;
+extern int revision;
 
 void spi_flasher();
 void detect();
diff --git a/board/gpio.h b/board/gpio.h
index 6246cea6..c0910fb6 100644
--- a/board/gpio.h
+++ b/board/gpio.h
@@ -54,7 +54,7 @@ void set_led(int led_num, int on) {
 
 
 // TODO: does this belong here?
-void periph_init() { 
+void periph_init() {
   // enable GPIOB, UART2, CAN, USB clock
   RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
   RCC->AHB1ENR |= RCC_AHB1ENR_GPIOBEN;
@@ -118,8 +118,7 @@ void set_can_mode(int can, int use_gmlan) {
       1        1        33kbit (normal)
       */
 
-#ifdef REVC
-    } else if (can == 3) {
+    } else if (revision == PANDA_REV_C && can == 3) {
       // A8,A15: disable normal mode
       set_gpio_mode(GPIOA, 8, MODE_INPUT);
       set_gpio_mode(GPIOA, 15, MODE_INPUT);
@@ -127,7 +126,6 @@ void set_can_mode(int can, int use_gmlan) {
       // B3,B4: enable gmlan mode
       set_gpio_alternate(GPIOB, 3, GPIO_AF11_CAN3);
       set_gpio_alternate(GPIOB, 4, GPIO_AF11_CAN3);
-#endif
     }
 
     // put gmlan transceiver in normal mode
@@ -149,11 +147,11 @@ void set_can_mode(int can, int use_gmlan) {
       set_gpio_alternate(GPIOB, 5, GPIO_AF9_CAN2);
       set_gpio_alternate(GPIOB, 6, GPIO_AF9_CAN2);
     } else if (can == 3) {
-      #ifdef REVC
+      if(revision == PANDA_REV_C){
         // B3,B4: disable gmlan mode
         set_gpio_mode(GPIOB, 3, MODE_INPUT);
         set_gpio_mode(GPIOB, 4, MODE_INPUT);
-      #endif
+      }
 
       // A8,A15: normal mode
       set_gpio_alternate(GPIOA, 8, GPIO_AF11_CAN3);
@@ -250,11 +248,10 @@ void gpio_init() {
 
   #ifdef PANDA
     // K-line enable moved from B4->B7 to make room for GMLAN on CAN3
-    #ifdef REVC
-      set_gpio_output(GPIOB, 7, 1);
-    #else
-      set_gpio_output(GPIOB, 4, 1);
-    #endif
+    if(revision == PANDA_REV_C)
+      set_gpio_output(GPIOB, 7, 1); // REV C
+    else
+      set_gpio_output(GPIOB, 4, 1); // REV AB
 
     // C12,D2: K-Line setup on UART 5
     set_gpio_alternate(GPIOC, 12, GPIO_AF8_UART5);
@@ -270,10 +267,12 @@ void gpio_init() {
     set_gpio_pullup(GPIOC, 11, PULL_UP);
   #endif
 
-  #ifdef REVC
+  if(revision == PANDA_REV_C) {
     // B2,A13: set DCP mode on the charger (breaks USB!)
-    /*set_gpio_output(GPIOB, 2, 0);
-    set_gpio_output(GPIOA, 13, 0);*/
-  #endif
-}
+    //set_gpio_output(GPIOB, 2, 0);
+    //set_gpio_output(GPIOA, 13, 0);
 
+    //set_gpio_output(GPIOA, 13, 1); //CTRL 1
+    //set_gpio_output(GPIOB, 2, 0);  //CTRL 2
+  }
+}
diff --git a/board/libc.h b/board/libc.h
index 29ef7ec6..6b3f5d27 100644
--- a/board/libc.h
+++ b/board/libc.h
@@ -12,29 +12,18 @@
 // **** shitty libc ****
 
 void clock_init() {
-  #ifdef USE_INTERNAL_OSC
-    // enable internal oscillator
-    RCC->CR |= RCC_CR_HSION;
-    while ((RCC->CR & RCC_CR_HSIRDY) == 0);
-  #else
-    // enable external oscillator
-    RCC->CR |= RCC_CR_HSEON;
-    while ((RCC->CR & RCC_CR_HSERDY) == 0);
-  #endif
+  // enable external oscillator
+  RCC->CR |= RCC_CR_HSEON;
+  while ((RCC->CR & RCC_CR_HSERDY) == 0);
 
   // divide shit
   RCC->CFGR = RCC_CFGR_HPRE_DIV1 | RCC_CFGR_PPRE2_DIV2 | RCC_CFGR_PPRE1_DIV4;
-  #ifdef USE_INTERNAL_OSC
+  #ifdef PANDA
     RCC->PLLCFGR = RCC_PLLCFGR_PLLQ_2 | RCC_PLLCFGR_PLLM_3 |
-                   RCC_PLLCFGR_PLLN_6 | RCC_PLLCFGR_PLLN_5 | RCC_PLLCFGR_PLLSRC_HSI;
+                   RCC_PLLCFGR_PLLN_6 | RCC_PLLCFGR_PLLN_5 | RCC_PLLCFGR_PLLSRC_HSE;
   #else
-    #ifdef PANDA
-      RCC->PLLCFGR = RCC_PLLCFGR_PLLQ_2 | RCC_PLLCFGR_PLLM_3 |
-                     RCC_PLLCFGR_PLLN_6 | RCC_PLLCFGR_PLLN_5 | RCC_PLLCFGR_PLLSRC_HSE;
-    #else
-      RCC->PLLCFGR = RCC_PLLCFGR_PLLQ_2 | RCC_PLLCFGR_PLLM_3 |
-                     RCC_PLLCFGR_PLLN_7 | RCC_PLLCFGR_PLLN_6 | RCC_PLLCFGR_PLLSRC_HSE;
-    #endif
+    RCC->PLLCFGR = RCC_PLLCFGR_PLLQ_2 | RCC_PLLCFGR_PLLM_3 |
+                   RCC_PLLCFGR_PLLN_7 | RCC_PLLCFGR_PLLN_6 | RCC_PLLCFGR_PLLSRC_HSE;
   #endif
 
   // start PLL
@@ -84,4 +73,3 @@ int memcmp(const void * ptr1, const void * ptr2, unsigned int num) {
   }
   return 0;
 }
-
diff --git a/board/llgpio.c b/board/llgpio.c
new file mode 100644
index 00000000..c7247d76
--- /dev/null
+++ b/board/llgpio.c
@@ -0,0 +1,37 @@
+#include "config.h"
+#include "llgpio.h"
+
+void set_gpio_mode(GPIO_TypeDef *GPIO, int pin, int mode) {
+  uint32_t tmp = GPIO->MODER;
+  tmp &= ~(3 << (pin*2));
+  tmp |= (mode << (pin*2));
+  GPIO->MODER = tmp;
+}
+
+void set_gpio_output(GPIO_TypeDef *GPIO, int pin, int val) {
+  if (val) {
+    GPIO->ODR |= (1 << pin);
+  } else {
+    GPIO->ODR &= ~(1 << pin);
+  }
+  set_gpio_mode(GPIO, pin, MODE_OUTPUT);
+}
+
+void set_gpio_alternate(GPIO_TypeDef *GPIO, int pin, int mode) {
+  uint32_t tmp = GPIO->AFR[pin>>3];
+  tmp &= ~(0xF << ((pin&7)*4));
+  tmp |= mode << ((pin&7)*4);
+  GPIO->AFR[pin>>3] = tmp;
+  set_gpio_mode(GPIO, pin, MODE_ALTERNATE);
+}
+
+void set_gpio_pullup(GPIO_TypeDef *GPIO, int pin, int mode) {
+  uint32_t tmp = GPIO->PUPDR;
+  tmp &= ~(3 << (pin*2));
+  tmp |= (mode << (pin*2));
+  GPIO->PUPDR = tmp;
+}
+
+int get_gpio_input(GPIO_TypeDef *GPIO, int pin) {
+  return (GPIO->IDR & (1 << pin)) == (1 << pin);
+}
diff --git a/board/llgpio.h b/board/llgpio.h
index 5c8e8ff8..2755215f 100644
--- a/board/llgpio.h
+++ b/board/llgpio.h
@@ -1,40 +1,23 @@
+#ifndef PANDA_LLGPIO_H
+#define PANDA_LLGPIO_H
+
 #define MODE_INPUT 0
 #define MODE_OUTPUT 1
 #define MODE_ALTERNATE 2
 #define MODE_ANALOG 3
 
-void set_gpio_mode(GPIO_TypeDef *GPIO, int pin, int mode) {
-  uint32_t tmp = GPIO->MODER;
-  tmp &= ~(3 << (pin*2));
-  tmp |= (mode << (pin*2));
-  GPIO->MODER = tmp;
-}
-
-void set_gpio_output(GPIO_TypeDef *GPIO, int pin, int val) {
-  if (val) {
-    GPIO->ODR |= (1 << pin);
-  } else {
-    GPIO->ODR &= ~(1 << pin);
-  }
-  set_gpio_mode(GPIO, pin, MODE_OUTPUT);
-}
-
-void set_gpio_alternate(GPIO_TypeDef *GPIO, int pin, int mode) {
-  uint32_t tmp = GPIO->AFR[pin>>3];
-  tmp &= ~(0xF << ((pin&7)*4));
-  tmp |= mode << ((pin&7)*4);
-  GPIO->AFR[pin>>3] = tmp;
-  set_gpio_mode(GPIO, pin, MODE_ALTERNATE);
-}
-
 #define PULL_NONE 0
 #define PULL_UP 1
-#define PULL_DOWN 2 
+#define PULL_DOWN 2
 
-void set_gpio_pullup(GPIO_TypeDef *GPIO, int pin, int mode) {
-  uint32_t tmp = GPIO->PUPDR;
-  tmp &= ~(3 << (pin*2));
-  tmp |= (mode << (pin*2));
-  GPIO->PUPDR = tmp;
-}
+void set_gpio_mode(GPIO_TypeDef *GPIO, int pin, int mode);
 
+void set_gpio_output(GPIO_TypeDef *GPIO, int pin, int val);
+
+void set_gpio_alternate(GPIO_TypeDef *GPIO, int pin, int mode);
+
+void set_gpio_pullup(GPIO_TypeDef *GPIO, int pin, int mode);
+
+int get_gpio_input(GPIO_TypeDef *GPIO, int pin);
+
+#endif
diff --git a/board/main.c b/board/main.c
index 687f1109..e36ebb61 100644
--- a/board/main.c
+++ b/board/main.c
@@ -1,27 +1,8 @@
-//#define DEBUG
-//#define DEBUG_USB
-//#define CAN_LOOPBACK_MODE
-//#define USE_INTERNAL_OSC
-//#define REVC
-
-#ifdef STM32F4
-  #define PANDA
-  #include "stm32f4xx.h"
-#else
-  #include "stm32f2xx.h"
-#endif
-
-#ifdef PANDA
-  #define ENABLE_CURRENT_SENSOR
-  #define ENABLE_SPI
-#endif
-
-#define USB_VID 0xbbaa
-#define USB_PID 0xddcc
+#include "config.h"
+#include "early.h"
 
 #define NULL ((void*)0)
 
-#include "early.h"
 
 // assign CAN numbering
 // old:         CAN1 = 1   CAN2 = 0