diff --git a/main.c b/main.c
index 9e2f023..f89b33e 100644
--- a/main.c
+++ b/main.c
@@ -90,20 +90,6 @@ const float gVoltageScale[VOLTAGE_SCALES] = {
     0.1, 0.2, 0.5, 1., 2.
 };
 
-#define TIME_SCALES 6
-const char * const gTimeScaleStr[TIME_SCALES] = {
-"100 ms", "50 ms", "20 ms", " 10 ms", "50 us", "20 us"
-};
-
-const uint64_t gTImeScale[TIME_SCALES] = {
-    100 * 1000 / PIXELS_PER_DIV,
-    50 * 1000 / PIXELS_PER_DIV,
-    20 * 1000 / PIXELS_PER_DIV,
-    10 * 1000 / PIXELS_PER_DIV,
-    50 / PIXELS_PER_DIV,
-    20 / PIXELS_PER_DIV,
-};
-
 int Trigger(bool rising);
 
 // start a pwm test signal
@@ -283,14 +269,6 @@ void handle_user_input() {
             case Down: // previous scale
                 local_options.voltage_scale = (local_options.voltage_scale + VOLTAGE_SCALES - 1) % VOLTAGE_SCALES;
                 break;
-            case Right: // next scale
-                local_options.time_scale = (local_options.time_scale + 1) % TIME_SCALES;
-                set_frequency(gTImeScale[local_options.time_scale]);
-                break;
-            case Left: // previous scale
-                local_options.time_scale = (local_options.time_scale + TIME_SCALES - 1) % TIME_SCALES;
-                set_frequency(gTImeScale[local_options.time_scale]);
-                break;
         }
 
         Semaphore_pend(options_sem, BIOS_WAIT_FOREVER);
@@ -336,7 +314,6 @@ void display_waveform(UArg arg1, UArg arg2)
         // info
         GrContextForegroundSet(&sContext, ClrWheat);
         GrStringDraw(&sContext, gVoltageScaleStr[local_options.voltage_scale], /*length*/ -1, /*x*/ 0, /*y*/ 0, /*opaque*/ false);
-        GrStringDraw(&sContext, gTimeScaleStr[local_options.time_scale], /*length*/ -1, /*x*/ 60, /*y*/ 0, /*opaque*/ false);
         snprintf(str, sizeof(str), "CPU Load %.1f%%", usage_percent);
         GrStringDraw(&sContext, str, /*length*/ -1, /*x*/ 0, /*y*/ HEIGHT - 10, /*opaque*/ false);
 
diff --git a/sampling.c b/sampling.c
index 51fca2c..1f32b1e 100644
--- a/sampling.c
+++ b/sampling.c
@@ -119,8 +119,6 @@ void start_sampler() {
     SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
     SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC1);
 
-    // timer for low-speed
-    SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER2);
     // ADC clock
     uint32_t pll_frequency = SysCtlFrequencyGet(CRYSTAL_FREQUENCY);
     uint32_t pll_divisor =
@@ -145,25 +143,3 @@ void start_sampler() {
     ADCSequenceDMAEnable(ADC1_BASE, 0); // enable DMA for ADC1 sequence 0
     ADCIntEnableEx(ADC1_BASE, ADC_INT_DMA_SS0); // enable ADC1 sequence 0 DMA interrupt
 }
-
-void set_frequency(uint64_t microseconds) {
-    if (microseconds == 1) {
-        ADCSequenceDisable(ADC1_BASE, 0);
-        // don't use a timer for high speed
-        ADCSequenceConfigure(ADC1_BASE, 0, ADC_TRIGGER_ALWAYS, 0);
-        ADCSequenceEnable(ADC1_BASE, 0);
-        return;
-    }
-
-    // initialize timer 2 in periodic mode
-    TimerDisable(TIMER2_BASE, TIMER_BOTH);
-    TimerConfigure(TIMER2_BASE, TIMER_CFG_PERIODIC);
-    #define MICROSECONDS_PER_SECOND 1000000
-    TimerLoadSet(TIMER2_BASE, TIMER_A, (uint32_t) ((uint64_t) gSystemClock * microseconds / MICROSECONDS_PER_SECOND) - 1);
-    TimerControlTrigger(TIMER2_BASE, TIMER_A, true);
-    TimerEnable(TIMER2_BASE, TIMER_A);
-
-    ADCSequenceDisable(ADC1_BASE, 0);
-    ADCSequenceConfigure(ADC1_BASE, 0, ADC_TRIGGER_TIMER, 0);
-    ADCSequenceEnable(ADC1_BASE, 0);
-}
diff --git a/src/sysbios/sysbios.aem4f b/src/sysbios/sysbios.aem4f
index 793a174..fe551a3 100644
Binary files a/src/sysbios/sysbios.aem4f and b/src/sysbios/sysbios.aem4f differ