diff --git a/firmware/retro_tech_fw/user/src/31fl3729.c b/firmware/retro_tech_fw/user/src/31fl3729.c
index 33a0966..2832a42 100644
--- a/firmware/retro_tech_fw/user/src/31fl3729.c
+++ b/firmware/retro_tech_fw/user/src/31fl3729.c
@@ -16,20 +16,17 @@
 
 void is31fl3729_init(uint8_t i2c_addr, uint8_t config, uint8_t global_current)
 {
-    uint8_t buf;
-
     // enable device
 #ifdef FL3729_SDB_PORT
     FL3729_SDB_PORT->BSHR = FL3729_SDB_PIN;
 #endif
 
     // reset config registers
-    buf = FL3729_RESET_VALUE;
-    i2c_write_addr1b(i2c_addr, FL3729_REG_RESET, &buf, 1);
+    i2c_write_reg_8b(i2c_addr, FL3729_REG_CONFIG, FL3729_RESET_VALUE);
 
     // write initial config
-    i2c_write_addr1b(i2c_addr, FL3729_REG_CONFIG, &config, 1);
-    i2c_write_addr1b(i2c_addr, FL3729_REG_G_CURRENT, &global_current, 1);
+    i2c_write_reg_8b(i2c_addr, FL3729_REG_CONFIG, config);
+    i2c_write_reg_8b(i2c_addr, FL3729_REG_G_CURRENT, global_current);
 }
 
 uint8_t is31fl3729_get_addr(uint8_t adpin)
@@ -40,21 +37,21 @@ uint8_t is31fl3729_get_addr(uint8_t adpin)
 
 void is31fl3729_set_global_current(uint8_t i2c_addr, uint8_t current)
 {
-    i2c_write_addr1b(i2c_addr, FL3729_REG_G_CURRENT, &current, 1);
+    i2c_write_reg_8b(i2c_addr, FL3729_REG_G_CURRENT, current);
 }
 
 void is31fl3729_set_scaling_current(uint8_t i2c_addr, uint8_t cs, uint8_t current)
 {
     if (cs > 0xf) return;
 
-    i2c_write_addr1b(i2c_addr, FL3729_REG_SCALING + cs, &current, 1);
+    i2c_write_reg_8b(i2c_addr, FL3729_REG_SCALING + cs, current);
 }
 
 /*
  * sets current limit of multiple outputs simultaneously, starting from CS1.
  * useful for initial register configuration.
  */
-void is31fl3729_set_scaling_current_multi(uint8_t i2c_addr, uint8_t *current, uint8_t count)
+void is31fl3729_set_scaling_current_multi(uint8_t i2c_addr, const uint8_t *current, uint8_t count)
 {
     if (!count) return;
     count &= 0xf;
@@ -67,9 +64,9 @@ void is31fl3729_set_scaling_current_multi(uint8_t i2c_addr, uint8_t *current, ui
  * sw:          first switch segment to update. usually set this to 1 for the first switch.
  *              if set to 0, will default to 1.
  * *out:        output data buffer
- * len:         length of buffer
+ * len:         length of buffer. up to end user to not exceed writing beyond register 0x90.
  */
-void is31fl3729_set_outputs(uint8_t i2c_addr, uint8_t sw, uint8_t *out, uint8_t len)
+void is31fl3729_set_outputs(uint8_t i2c_addr, uint8_t sw, const uint8_t *out, uint8_t len)
 {
     if (!sw) sw = 1;
 
diff --git a/firmware/retro_tech_fw/user/src/31fl3729.h b/firmware/retro_tech_fw/user/src/31fl3729.h
index a243bbf..3e4f0c9 100644
--- a/firmware/retro_tech_fw/user/src/31fl3729.h
+++ b/firmware/retro_tech_fw/user/src/31fl3729.h
@@ -25,24 +25,24 @@
 #define FL3729_REG_OUTPUT       0x01
 #define FL3729_REG_SCALING      0x90
 #define FL3729_REG_CONFIG       0xA0
-#define FL3729_REG_G_CURRENT    0xA1    // global current
-#define FL3729_REG_PUPD         0xB0    // pull up / pull down
-#define FL3729_REG_SS           0xB1    // spread spectrum
+#define FL3729_REG_G_CURRENT    0xA1        // global current
+#define FL3729_REG_PUPD         0xB0        // pull up / pull down
+#define FL3729_REG_SS           0xB1        // spread spectrum
 #define FL3729_REG_PWM          0xB2
 #define FL3729_REG_RESET        0xCF
 
 
-#define FL3729_GCC_MAX          64      // maximum global current level
+#define FL3729_GCC_MAX          64          // maximum global current level
 
-#define FL3729_CONF_SHDN_ENA    0
-#define FL3729_CONF_SHDN_DIS    ((1 << 0) << 0)
+#define FL3729_CONF_SSD_SHDN    (0 << 0)    // software shutdown
+#define FL3729_CONF_SSD_NRML    (1 << 0)    // normal operation
 
-#define FL3729_CONF_OSDE_OFF    0
-#define FL3729_CONF_OSDE_OPEN   ((1 << 0) << 1)
-#define FL3729_CONF_OSDE_SHORT  ((1 << 1) << 1)
+#define FL3729_CONF_OSDE_OFF    (0 << 1)
+#define FL3729_CONF_OSDE_OPEN   (1 << 1)
+#define FL3729_CONF_OSDE_SHORT  (2 << 1)
 
-#define FL3729_CONF_LOGIC_LOLEV 0
-#define FL3729_CONF_LOGIC_HILEV ((1 << 0) << 3)
+#define FL3729_CONF_LOGIC_LOLEV (0 << 3)
+#define FL3729_CONF_LOGIC_HILEV (1 << 3)
 
 #define FL3729_CONF_MATRIX_9x15 0x00
 #define FL3729_CONF_MATRIX_8x16 0x10
@@ -68,25 +68,15 @@
 
 
 
-
-/*
-typedef struct IS31FL3729_Conf {
-    uint8_t ad_pin;
-    uint8_t config;
-    uint8_t global_brightness;
-} IS31FL3729_Conf;
-*/
-
-
 void is31fl3729_init(uint8_t i2c_addr, uint8_t config, uint8_t global_current);
 
 uint8_t is31fl3729_get_addr(uint8_t adpin);
 
 void is31fl3729_set_global_current(uint8_t i2c_addr, uint8_t current);
 void is31fl3729_set_scaling_current(uint8_t i2c_addr, uint8_t cs, uint8_t current);
-void is31fl3729_set_scaling_current_multi(uint8_t i2c_addr, uint8_t *current, uint8_t count);
+void is31fl3729_set_scaling_current_multi(uint8_t i2c_addr, const uint8_t *current, uint8_t count);
 
-void is31fl3729_set_outputs(uint8_t i2c_addr, uint8_t sw, uint8_t *out, uint8_t len);
+void is31fl3729_set_outputs(uint8_t i2c_addr, uint8_t sw, const uint8_t *out, uint8_t len);
 
 
 
diff --git a/firmware/retro_tech_fw/user/src/i2c.c b/firmware/retro_tech_fw/user/src/i2c.c
index 6299ec6..d32145f 100644
--- a/firmware/retro_tech_fw/user/src/i2c.c
+++ b/firmware/retro_tech_fw/user/src/i2c.c
@@ -100,7 +100,7 @@ uint8_t i2c_read_reg_8b(uint8_t addr, uint8_t reg)
     return dat;
 }
 
-int8_t i2c_write_addr1b(uint8_t addr, uint8_t reg, uint8_t *data, uint8_t len)
+int8_t i2c_write_addr1b(uint8_t addr, uint8_t reg, const uint8_t *data, uint8_t len)
 {
     timeout = I2C_TIMEOUT;
     while((I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) != RESET) && timeout--);
@@ -136,7 +136,7 @@ int8_t i2c_write_addr1b(uint8_t addr, uint8_t reg, uint8_t *data, uint8_t len)
     return 0;
 }
 
-void i2c_write_reg_8b(uint8_t addr, uint8_t reg, uint8_t dat)
+void i2c_write_reg_8b(uint8_t addr, uint8_t reg, const uint8_t dat)
 {
     i2c_write_addr1b(addr, reg, &dat, 1);
 }
diff --git a/firmware/retro_tech_fw/user/src/i2c.h b/firmware/retro_tech_fw/user/src/i2c.h
index c3c3568..9cc9b13 100644
--- a/firmware/retro_tech_fw/user/src/i2c.h
+++ b/firmware/retro_tech_fw/user/src/i2c.h
@@ -14,10 +14,10 @@
 void i2c_init();
 
 int8_t i2c_read_addr1b(uint8_t addr, uint8_t reg, uint8_t *data, uint8_t len);
-int8_t i2c_write_addr1b(uint8_t addr, uint8_t reg, uint8_t *data, uint8_t len);
+int8_t i2c_write_addr1b(uint8_t addr, uint8_t reg, const uint8_t *data, uint8_t len);
 
 uint8_t i2c_read_reg_8b(uint8_t addr, uint8_t reg);
-void i2c_write_reg_8b(uint8_t addr, uint8_t reg, uint8_t dat);
+void i2c_write_reg_8b(uint8_t addr, uint8_t reg, const uint8_t dat);
 
 int8_t i2c_ack_poll(uint8_t devaddr);
 
diff --git a/firmware/retro_tech_fw/user/src/led.c b/firmware/retro_tech_fw/user/src/led.c
index f2631fc..615faf3 100644
--- a/firmware/retro_tech_fw/user/src/led.c
+++ b/firmware/retro_tech_fw/user/src/led.c
@@ -48,7 +48,7 @@ void led_init()
     uint8_t buf[FL3729_CS_OUTPUTS] = {0xff};
 
     is31fl3729_init(FL3729_ADDR,
-                    FL3729_CONF_SHDN_DIS | FL3729_CONF_OSDE_OFF | FL3729_CONF_MATRIX_2x16,
+                    FL3729_CONF_SSD_NRML | FL3729_CONF_OSDE_OFF | FL3729_CONF_MATRIX_2x16,
                     LED_INIT_CURRENT);
 
     for (i = 0; i < FL3729_CS_OUTPUTS; i++) buf[i] = LED_INIT_SCALING;
@@ -83,6 +83,8 @@ void led_send()
         out[cursor_map[2]] = cursor[2];
 
         is31fl3729_set_outputs(FL3729_ADDR, 1, out, 16+15);
+
+        led_updated = 0;
     }
 }