AP_HAL: update prescaler tests

libraries/AP_HAL/tests/test_prescaler.cpp

@@ -11,24 +11,24 @@ protected:
         const uint32_t prescaler = AP_HAL::RCOutput::calculate_bitrate_prescaler(clock, target_rate, is_dshot);
         // we would like at most a 1% discrepancy in target versus actual
         const float rate_delta = fabsf(float(clock / prescaler) - target_rate) / target_rate;
-        EXPECT_TRUE(rate_delta < 0.20f);
+        EXPECT_TRUE(rate_delta < 0.13f);
     }
 };
 
 TEST_P(PrescalerParameterizedTestFixture, DShot150) {
-    test_prescaler(GetParam(), 150000 * 20, true);
+    test_prescaler(GetParam(), 150000 * 8, true);
 }
 
 TEST_P(PrescalerParameterizedTestFixture, DShot300) {
-    test_prescaler(GetParam(), 300000 * 20, true);
+    test_prescaler(GetParam(), 300000 * 8, true);
 }
 
 TEST_P(PrescalerParameterizedTestFixture, DShot600) {
-    test_prescaler(GetParam(), 600000 * 20, true);
+    test_prescaler(GetParam(), 600000 * 8, true);
 }
 
 TEST_P(PrescalerParameterizedTestFixture, DShot1200) {
-    test_prescaler(GetParam(), 1200000 * 20, true);
+    test_prescaler(GetParam(), 1200000 * 8, true);
 }
 
 TEST_P(PrescalerParameterizedTestFixture, Passthrough) {
@@ -36,11 +36,11 @@ TEST_P(PrescalerParameterizedTestFixture, Passthrough) {
 }
 
 TEST_P(PrescalerParameterizedTestFixture, NeoPixel) {
-    test_prescaler(GetParam(), 800000 * 20, false);
+    test_prescaler(GetParam(), 800000 * 11, false);
 }
 
 TEST_P(PrescalerParameterizedTestFixture, ProfiLED) {
-    test_prescaler(GetParam(), 1500000 * 20, false);
+    test_prescaler(GetParam(), 1500000 * 11, false);
 }
 
 INSTANTIATE_TEST_CASE_P(