diff --git a/main.c b/main.c
--- a/main.c
+++ b/main.c
@@ -48,6 +48,7 @@ int main(void)
     /* Initialize all configured peripherals */
     init_gpio();
     MX_USB_DEVICE_Init();
+//    set.usb_plugged = 
 
     // USB startup delay
     HAL_Delay(1000);
@@ -164,30 +165,38 @@ void update_temp() {
 
     // Assemble data array into one var
     uint16_t temp_pre = rxdatal[0] | (rxdatah[0]<<8);
-
-    if(temp_pre & 0b0000000000000010) {
+/*
+    if(temp_pre & 0b010) {
         ssd1306_clearscreen();
-        HAL_Delay(100); // FIXME: remove?
+        HAL_Delay(400); // FIXME: remove?
         status.tc_errno = 4;
         status.state = STATE_TC_ERROR;
         status.temp = 0;
         status.temp_frac = 0;
-    }
-    else if(temp_pre & 0b0000000000000001 && !set.ignore_tc_error) {
+    } */
+    if(temp_pre & 0b001 && !set.ignore_tc_error) {
         status.tc_errno = 1;
-        HAL_Delay(100); // FIXME: remove?
+        HAL_Delay(400); // FIXME: remove?
         status.state_resume = status.state;
         status.state = STATE_TC_ERROR;
         status.temp = 0;
         status.temp_frac = 0;
-    }
+    }/*
+    else if(temp_pre & 0b100 && !set.ignore_tc_error) {
+        status.tc_errno = 8;
+        HAL_Delay(400); // FIXME: remove?
+        status.state_resume = status.state;
+        status.state = STATE_TC_ERROR;
+        status.temp = 0;
+        status.temp_frac = 0;
+    }*/
     else 
     {
-        if(status.state == STATE_TC_ERROR)
-        {
-            status.state = status.state_resume;
-            ssd1306_clearscreen();
-        }
+        //if(status.state == STATE_TC_ERROR)
+        //{
+        //    status.state = status.state_resume;
+        //    ssd1306_clearscreen();
+        //}
 
         uint8_t sign = status.temp >> 15;// top bit is sign
 
@@ -282,25 +291,27 @@ int16_t update_pid(uint16_t k_p, uint16_
 uint32_t last_ssr_on = 0;
 uint32_t last_vcp_tx = 0;
 uint32_t last_led = 0;
+uint32_t last_pid = 0;
 int16_t ssr_output = 0; // Duty cycle of ssr, 0 to SSR_PERIOD 
 
 // Turn SSR output on/off according to set duty cycle.
 // TODO: Eventually maybe replace with a very slow timer or something. Double-check this code...
 void process()
 {
-    update_temp(); // Read MAX31855
 
     uint32_t ticks = HAL_GetTick();
 
     if(ticks - last_led > 400) 
     {
-        HAL_GPIO_TogglePin(LED_POWER);
         last_led = ticks;
     }
 
-    // Every 200ms, set the SSR on unless output is 0
-    if((ticks - last_ssr_on > SSR_PERIOD))
+    if((ticks - last_pid > PID_PERIOD))
     {
+        update_temp(); // Read MAX31855
+
+    HAL_GPIO_TogglePin(LED_POWER);
+
         if(status.pid_enabled) 
         {
             // Get ssr output for next time
@@ -313,6 +324,13 @@ void process()
             ssr_output = 0;
         }
 
+        last_pid = ticks;
+    }
+
+    // Every 200ms, set the SSR on unless output is 0
+    if((ticks - last_ssr_on > SSR_PERIOD))
+    {
+
         // Only support heating (ssr_output > 0) right now
         if(ssr_output > 0) {
 
@@ -340,7 +358,8 @@ void process()
         tempstr[numlen] = '\r';
         tempstr[numlen+1] = '\n';
 
-        CDC_Transmit_FS(tempstr, numlen+2);
+//        if(set.usb_plugged)
+//            CDC_Transmit_FS(tempstr, numlen+2);
        // while(CDC_Transmit_FS("\r\n", 2) == USBD_BUSY);
 
         last_vcp_tx = ticks;