teatimer

A simple kitchen timer implemented in digital logic on a Lattice MachXO2 CPLD.

(It's brighter in person.)

Details

• Features
  • Large 7-segment display
  • Count-down/count-up timer
  • Alarm and silent modes
  • AAA battery powered
• Limitations
  • 10 hour battery life
• ICs
  • Lattice MachXO2-256 CPLD
  • SG-3030JC 32.768 kHz Oscillator
  • TLV61225 Boost Converter 1.5V -> 3.3V
• Dimensions of 80mm x 49mm
• Power consumption of ~100mA @ 1.5V (mostly from LEDs)

Project Structure

• README.md - this README
• teatimer.v - Verilog source
• teatimer_tb.v - Verilog test bench
• Makefile - Makefile for simulation
• hw/ - Schematic and layout
  • teatimer.sch - Eagle schematic
  • teatimer.brd - Eagle layout
  • teatimer-sch.png - Schematic image
  • teatimer-brd.png - Layout image
  • gerbers/ - Gerbers
• diamond/ - Lattice Diamond project
  • teatimer.ldf - Project file
  • teatimer.v - Symlinked Verilog source
  • teatimer.lpf - Constraints
  • teatimer.jed - JEDEC bitstream
• misc/ - Miscellaneous scripts

Design Summary

The design uses 67 bits of state, 91% of the LUTs for logic, and all of the I/O.

Number of registers:     67 out of   322 (21%)
   PFU registers:           63 out of   256 (25%)
   PIO registers:            4 out of    66 (6%)
Number of SLICEs:       117 out of   128 (91%)
   SLICEs as Logic/ROM:    117 out of   128 (91%)
   SLICEs as RAM:            0 out of    96 (0%)
   SLICEs as Carry:         27 out of   128 (21%)
Number of LUT4s:        232 out of   256 (91%)
   Number used as logic LUTs:        178
   Number used as distributed RAM:     0
   Number used as ripple logic:       54
   Number used as shift registers:     0
Number of PIO sites used: 18 + 4(JTAG) out of 22 (100%)
Number of block RAMs:  0 out of 0
Number of GSRs:  1 out of 1 (100%)

Datasheets

• U1, Lattice MachXO2 CPLD, LCMXO2-256HC-4SG32C - family datasheet
• U2, 32.768 kHz Oscillator, SG-3030JC32.7680KB:ROHS - datasheet
• U3, Boost Converter, TLV61225DCKR - datasheet
• DISP1, 7-segment Display, HDSP-B03E - datasheet
• SP1, 4kHz Buzzer, PKM13EPYH4000-A0 - datasheet

Schematic

Layout

Bill of Materials

Qty	Part	Refdes	Digi-key Part Number	Total Price
1	Lattice MachXO2-256 CPLD	U1	220-2636-ND	2.830
1	Oscillator 32.768kHz	U2	SG-3030JC32.7680KB:ROHS-ND	1.398
1	TLV61225 Boost Converter	U3	296-36756-1-ND	0.775
1	NPN BJT (Buzzer Driver)	Q1	BC817-40LT1GOSCT-ND	0.103
1	PMOS FET (Polarity Prot.)	Q2	SI2365EDS-T1-GE3CT-ND	0.297
4	Tactile Switch (Buttons)	SW1-SW4	CKN9085CT-ND	0.776
1	Slide Switch (Power)	SW5	CKN9558-ND	0.648
1	7-segment LED Display	DISP1	516-2745-ND	2.821
1	Buzzer 4kHz	SP1	490-4698-ND	0.499
1	Battery Connector AAA	J1	36-2466-ND	0.928
1	SMD Header 1x6	JP1	952-3235-ND	0.711
1	Inductor 4.7uH	L1	1276-6213-1-ND	0.153
1	Capacitor 47uF 0603	C1	311-1897-1-ND	0.322
2	Capacitor 10uF 0603	C2,C3	587-3258-1-ND	0.238
10	Capacitor 0.1uF 0603	C4-C13	1276-1005-1-ND	0.073
6	Resistor 10K 0603	R1,R3,R5,R7,R9,R19	311-10KGRCT-ND	0.033
4	Resistor 100K 0603	R2,R4,R6,R8	311-100KGRCT-ND	0.029
1	Resistor 1K 0603	R10	311-1.0KGRCT-ND	0.010
1	Resistor 4.7K 0603	R21	311-4.7KGRCT-ND	0.010
1	Resistor 0.0 0603	R20	311-0.0GRCT-ND	0.010
8	Resistor 300 0603	R11-R18	311-300GRCT-ND	0.044
4	Standoffs M3 16mm Nylon	-	952-2188-ND	1.504
4	Screws M3 Nylon	-	36-29341-ND	0.748
1	PCB Lead-free, Shipped	-	-	3.240
	Total per unit			18.20

Price breaks based on quantities to build 10 units. All prices in US dollars.

Known Issues

• Silent mode is not 100% silent (design oversight)
• Limited battery life (~10 hours)

Hardware Change Log

• v1 - 01/30/2017
  • Initial release

RTL Change Log

• v0.1.0 - 01/30/2017
  • Initial release

License

teatimer is CC-BY-4.0 licensed. See the included LICENSE file.