Digital Clock

Contents of Readme

1. About
2. System Description
   1. Clockwork
   2. Date module
   3. Alarm module
   4. 24 hour to 12 hour converter
3. Port Descriptions
   1. Clockwork
   2. Date module
   3. Alarm module
   4. 24 hour to 12 hour converter
4. Simulation
5. Test
6. Status
7. Licence

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About

This project is a digital clock with date function. Currently works with 24h time format. It is still under development.

System Description

Functionalities are seperated into different files, follows as:

• clockwork.v: Hours, Minutes and Seconds
• clockcalendar.v: Days, Months and Years
• alarm.v: Alarm with an enable control
• h24toh12.v: 24 hour to 12 hour converter

Decimal modules always keep values in a decimal representation. e.g. fourteen is represented as 0x0E in hexadecimal modules and as 0x14 in decimal modules.

clockWork:

This module provides basic time functionality. It uses a 1 Hz clock. This module does not provide a seperate reset signal, thus resetting should be done via time overwrite signal, time_ow.

In hexadecimal module, clockWorkHex, time is kept in 17 bits. Most significant 5 bits represent hour, following 6 bits represent minute and 6 least significant bits represent seconds.

In decimal module, clockWorkDec, time is kept in 20 bits. Most significant 6 bits represent hour, following 7 bits represent minute and 7 least significant bits represent seconds.

clockcalendar:

This module provides an "add-on" to provide date functionality. It uses current hour to keep track of date. Similar to clockWork module, resetting should be done via date overwrite signal, date_ow.

In hexadecimal module, clockCalendarHex, date is kept in 9 + year bits. Year bits determined via parameter YEARRES. Most significant 5 bits represent day, following 4 bits represent month and remaining bits represent year. Default value for YEARRES is 12 bits.

Two decimal modules are designed. At both of the modules, most significant 6 bits represent day, following 5 bits represent month and remaining bits represent year. In clockCalendarDec4, year is kept in 4 digits with 14 bits; and in clockCalendarDec2, year is kept in 2 digits with 8 bits.

alarm:

This module provides an "add-on" alarm. Alarm can be enabled via en_in. Signal ring is set when alarm is ring. And it is kept high until end_ring is set.

Alarm is not sensitive to the seconds.

File alarm.v contains two modules alarmHex and alarmDec, one for hexadecimal other one for decimal modules. However only diffrence between those modules is the size of the registers.

h24Toh12:

Combinational "add-on" module to convert 24 hour format to 12 hour format.

Port Descriptions

I: Input O: Output

In width column: Hexadecimal/Decimal

clockWork:

Port	Type	Width	Description
clk_1hz	I	1	1 Hz Clock
time_in	I	17/20	Time input
time_out	O	17/20	Time output
time_ow	I	1	Time overwrite

clockcalendar:

Port	Type	Width	Description
clk	I	1	System Clock
hour_in	I	5/6	Current hour
date_in	I	YEARRES+9/25/19	Date input
date_out	O	YEARRES+9/25/19	Date output
date_ow	I	1	Date overwrite

YEARRES parameter determines the size of year register, default is 12 bits.

alarm:

Port	Type	Width	Description
clk	I	1	System Clock
rst	I	1	System Reset
en_in	I	1	Enable Alarm
time_in	I	11/13	Time input (No seconds)
time_set_in	I	11/13	Time setting input (No seconds)
set_time	I	1	Set Alarm Time
ring	0	1	Alarm signal
end_ring	I	1	Stop Alarm

h24Toh12:

Port	Type	Width	Description
hour24	I	5/6	Hour in 24 hour format
nAM_PM	O	1	AM/PM indicator, High when PM
hour12	O	4/5	Hour in 12 hour format

Simulation

testbench_basic.v is used to simulate clockWorkHex @ clockwork.v and clockCalendarHex @ clockcalendar.v

testbench_alarm.v is used to simulate alarmHex @ alarm.v

testbench_h24h12.v is used to simulate h24Toh12Hex and h24Toh12Dec @ h24toh12.v

testbench_decClkwork.v is used to simulate clockWorkDec @ clockwork.v

testbench_decCal.v is used to simulate clockCalendarDec4 and clockCalendarDec2 @ clockcalendar.v

Test

Test 1 Hex modules (on 20 March 2021)

Hexadecimal modules in clockwork.v, clockcalendar.v, alarm.v and h24toh12.v are tested with testboard_main.v and Basys3.xdc. Special cases and a few examples of orinary cases are tested.

States:

Test board have four states; IDLE, get date, get time and get alarm. In IDLE state is the default state where system works. Other three states used to change/set time and date information.

I/O:

Eight rightmost switches are reserved to get data from user. How many switches actually used depends on entered data. Eight leftmost switches reserved for configurations. Leftmost switch (SW[15]) is used to control hour format, 12h or 24h. Following three switches (sw[14:12]) used to select seven segment display (ssd) data in IDLE state. In other states, values if data switches (sw[7:0]) are shown. Table below shows mapping of sw[14:12] values to display content. Following switch (SW[11]) is used to enable alarm.

sw[14:12] value	Displayed Content	Active Digits
0	Seconds	Right Half
1	Hours:Minutes	All
2	Day:Month	All
3	Year	Right Half
4	Switch val	Right Half
?	Empty	None

Dots on the ssd is used to indicate AM/PM.

LEDs are used to show status information. Two leftmost LEDs show stepCounter (will be explaned later), following two LEDs show state informarion. Rightmost LED is used as alarm. Remaining LEDs tied to ground.

In IDLE mode all buttons except center and down one used to change the state of the test board. Center button is reset and down button used to silence alarm. Up button used to set time, left button used to set date and right button used to set alarm time. While getting data, any button (other than center) will advence to next step. Which part of the data is gathered depends on which state and step are we. Table below shows gathered data:

stepCounter	getTIME	getDATE	setALRM
0	Hour (5 bits)	Year (7 bits)	Hour (5 bits)
1	Minute (6 bits)	Month (4 bits)	Minute (6 bits)
2	-	Day (6 bits)	-

Anything that is not taken from the switches conneced to 0.

Tested Cases:

• clockWorkHex @ clockwork.v:
  • Seconds in Minute
  • New Minute
  • New Hour
  • New Day
• clockCalendarHex @ clockcalendar.v:
  • New Year
  • Ordinary February
  • Special Case February
  • End of a random month with 30 days before July
  • End of a random month with 31 days before July
  • End of a random month with 30 days after August
  • End of a random month with 31 days after August
• alarm @ alarm.v:
  • Tested for one case when enabled and one disabled.
• h24Toh12Hex @ h24toh12.v:
  • Two random cases for both AM and PM tested.
  • Midnight and Noon are tested.

(Synthesized) Utilization on Artix-7 XC7A35T-1CPG236C:

• clockWorkHex @ clockwork.v:
  • Slice LUTs: 80
  • Slice Registers: 51
• clockCalendarHex @ clockcalendar.v:
  • Slice LUTs: 106
  • Slice Registers: 78
• alarmHex @ alarm.v:
  • Slice LUTs: 6
  • Slice Registers: 13
• h24Toh12Hex @ h24toh12.v:
  • Slice LUTs: 2

Test 2 Dec modules (on 22 April 2021)

testmodule_dec.v includes a test module for clockWorkDec @ clockwork.v, alarmDec @ alarm.v, h24Toh12Dec @ h24toh12.v, and clockCalendar2Dec and clockCalendar4Dec @ clockcalendar.v. Similar logic as Hexadecimal module tests (testboard_main.v) and same constrains (Basys3.xdc) is used for testing. Register sizes changed accordingly. Each module added as a seperate block and connected to test module in block desing. One can refer Test 1 for more information about test logic.

Tested Cases:

• clockWorkDec @ clockwork.v:
  • Seconds in Minute
  • New Minute
  • New Hour
  • New Day
• clockCalendar2Dec @ clockcalendar.v:
  • New Year
  • Ordinary February
  • Special Case February
  • End of a random month with 30 days before July
  • End of a random month with 31 days before July
  • End of a random month with 30 days after August
  • End of a random month with 31 days after August
• alarmDec @ alarm.v:
  • Tested for one case when enabled and one disabled.
• h24Toh12Dec @ h24toh12.v:
  • Two random cases for both AM and PM tested.
  • Midnight and Noon are tested.

Note:clockCalendar4Dec module did not update it's values with date_ow singnal in test.

(Synthesized) Utilization on Artix-7 XC7A35T-1CPG236C:

• clockWorkDec @ clockwork.v:
  • Slice LUTs: 90
  • Slice Registers: 60
• clockCalendar2Dec @ clockcalendar.v:
  • Slice LUTs: 109
  • Slice Registers: 75
• clockCalendar4Dec @ clockcalendar.v:
  • Slice LUTs: 161
  • Slice Registers: 93
• alarmDec @ alarm.v:
  • Slice LUTs: 7
  • Slice Registers: 15
• h24Toh12Dec @ h24toh12.v:
  • Slice LUTs: 4

Status

Last Simulation:

• clockwork.v: 21 April 2021 with Icarus Verilog
• clockcalendar.v: 22 April 2021 with Icarus Verilog
• alarm.v: 28 April 2020 with Icarus Verilog
• h24toh12.v: 21 April 2021 with Icarus Verilog

Last Test:

• Hexadecimal modules: 20 March 2021, on Digilent Basys 3.

• Decimal modules: 22 April 2021, on Digilent Basys 3.

Licence

CERN Open Hardware Licence Version 2 - Weakly Reciprocal