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

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

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.