diff --git a/signals/nist.txt b/signals/nist.txt
new file mode 100644
index 0000000000000000000000000000000000000000..40af02f10fa7c9f085e1c0b4f4fdd2548f3a1e9c
--- /dev/null
+++ b/signals/nist.txt
@@ -0,0 +1,33 @@
+dust:~/3rd/SP800-90B_EntropyAssessment/cpp ./ea_non_iid ~/own/caprand/signals/l17-num2.bin8 8 
+
+Running non-IID tests...
+
+Running Most Common Value Estimate...
+
+Running Entropic Statistic Estimates (bit strings only)...
+
+Running Tuple Estimates...
+
+Running Predictor Estimates...
+
+H_original: 6.043898
+H_bitstring: 0.475864
+min(H_original, 8 X H_bitstring): 3.806913
+
+---------
+
+dust:~/3rd/SP800-90B_EntropyAssessment/cpp ./ea_non_iid ~/own/caprand/signals/20const.bin8 8 
+
+Running non-IID tests...
+
+Running Most Common Value Estimate...
+
+Running Entropic Statistic Estimates (bit strings only)...
+
+Running Tuple Estimates...
+
+Running Predictor Estimates...
+
+H_original: 2.906981
+H_bitstring: 0.435290
+min(H_original, 8 X H_bitstring): 2.906981
diff --git a/src/cap.rs b/src/cap.rs
index dccb433b2403e8f009b1a2c10fa0c8397031dad8..011055673a836af993f009c63066532d3cd46654 100644
--- a/src/cap.rs
+++ b/src/cap.rs
@@ -63,7 +63,7 @@ GPIO13
 // on reading.
 const LOW_OVER: u32 = 1000;
 // Power of two for faster modulo
-const HIGH_OVER: u32 = LOW_OVER + 1024;
+const HIGH_OVER: u32 = LOW_OVER + 1023;
 
 // Assume worst case from rp2040 datasheet.
 // 3.3v vdd, 2v logical high voltage, 50kohm pullup, 0.01uF capacitor, 125Mhz clock.