Fixed spelling mistakes

Author: ndornseif

README.md

@@ -4,61 +4,61 @@ Measures the frequency of mains power.
 ## Overview
 This device was built as an exercise in digital electronics.  
 It uses a reciprocal frequency counter approach to measure the frequency of the mains voltage supplying it.   
-Using two SN74LV8154N 32bit counters, it counts pulses of the mains signal and the reference clock.  
-The start and end of measurement are syncronized to the input signal using a D-FlipFlop to open the main gate.  
+Using two SN74LV8154N 32-bit counters, it counts pulses of the mains signal and the reference clock.  
+The start and end of the measurement are synchronized to the input signal, using a D-Flip-Flop to open the main gate.  
 This eliminates the influence of gate time accuracy on the measurement.  
 The measurement result is then calculated as follows:  
 $f_{measured} = \frac{n_{SignalCounter}}{n_{RefCounter}} \times f_{Ref}$   
-The measured value is send out over serial (J2).  
-Find a graph explaining the signal flow [here](Charts/Signalflow.pdf).
+The measured value is sent out over serial (J2).  
+Find a graph explaining the signal flow [here](Charts/Signalflow.pdf).  
 
 ## Board overview
-![Topside of circuit board](Images/board_overview.png)
+![Topside of the circuit board](Images/board_overview.png)  
 
 ## Connectors/Headers
-- GND: Ground connection for scope ground clips.
+- GND: Ground connection for scope ground clips.  
 - TP4: DC voltage rails.
-- J2: Serial interface. Connected to D0/D1 of Arduino. (5V max.)
+- J2: Serial interface. Connected to D0 and D1 of the Arduino. (5V max.)
 - J5: Debug pins. (SBUS0, SBUS1, SBUS2, SBUSE, CounterClear, GateTime, CounterRegClock, Reset)
 - J6: CBUS. Used to read out the counter values.
-- CN1: Mains input. Fuse with 5x20mm 32mA glass fuse in F1.
-- CN2: External reference input. BNC. 0-5V square wave only. HiZ input.
+- CN1: Mains input. Fuse with a 5x20mm 32mA glass fuse in F1.
+- CN2: External reference input. BNC. 0–5V square wave only. HiZ input.
 
 ## Jumpers
-- JMP1 (J3): Selects if measured signal is inverted. This should not affect the measurement. Recommended setting is INV.
-- JMP2 (J4): Selects external or internal reference clock. Check TP11 for selected signal.
+- JMP1 (J3): Selects if the measured signal is inverted. This should not affect the measured value. The recommended setting is INV.
+- JMP2 (J4): Selects an external or internal reference clock. Check TP11 for the selected signal.
 
 ## Test points
 - TP1:  Offset voltage to compensate for the clipping diode drop. (~ 500mV DC)
-- TP2:  Divided and clipped transformer output voltage. (~ 4V<sub>p</sub> half wave rectified sine)
+- TP2:  Divided and clipped transformer output voltage. (~ 4V<sub>p</sub> half-wave rectified sine)
 - TP3:  Unregulated rectified and smoothed transformer voltage. (> 17V DC)
-- TP4:  DC Supply rails. (+5V and +3.3V DC)
-- TP5:  Reference oscillator signal. (1MHz or 10MHz 0-5V square wave)
-- TP6:  Gate-Enable signal from FlipFlop. High if main gate is open and measurement running.
+- TP4:  DC supply rails. (+5V and +3.3V DC)
+- TP5:  Reference oscillator signal. (1 MHz or 10 MHz 0–5V square wave)
+- TP6:  Gate-Enable signal from Flip-Flop. High if the main gate is open and the measurement is running.
 - TP7:  Input to the signal counter.
 - TP8:  Input to the reference counter.
 - TP9:  Transformer output voltage to measurement circuit. (> 12V AC)
 - TP10: External reference clock input.
-- TP11: Reference input to the main gate. Should show the same signal as TP10 or TP5 depending on JMP2 (Clock select).
-- TP12: Signal input to the main gate. (0-5V square wave with same frequency as mains)
+- TP11: Reference input to the main gate. Should show the same signal as TP10 or TP5 depending on JMP2 (clock select).
+- TP12: Signal input to the main gate. (0-5V square wave with the same frequency as the mains)
 
 ## Trimmers
 - RP1:  Use this pot to adjust the voltage of the 5V rail.  
 
 ## Firmware 
 Find the firmware for this project in this [repository](https://github.com/ndornseif/MSM501-Firmware).  
-You can just upload it using the official Arduino IDE onto the Arduino nano (U7).  
+You can just upload it using the official Arduino IDE onto the Arduino Nano (U7).  
 Remove the Arduino from the board when uploading firmware.  
-Measurement results are in uHz and send out over serial.  
-They are send as ASCII and LF, CR seperated.  
-Default parameters: 115200 baud, 8 data, 1 stop, no parity
+Measurement results are in uHz and sent out over serial.  
+They are sent as ASCII and separated by LF and CR.   
+Default parameters: 115200 baud, 8 data, 1 stop, no parity  
 
 ## Example data
 ![Mains Frequency in Germany](Images/freq_23-06-03.png)
 
 ## Considerations
-Trying to power the Arduino through its USB header while the device is connected to mains is not recommended.  
-Use J2 (Serial) for communication while mains is applied.
+Trying to power the Arduino through its USB header while the device is connected to the mains is not recommended.  
+Use J2 (serial) for communication while mains is applied.  
 
 ## Other
 Published under CERN-OHL-S license.