portable timer

characteristic

TM1650 drives 4-digit 8-segment 0.8-inch digital tube for display;

Onboard DS1302 clock IC, accurate timing;

Onboard buzzer is responsible for reminding time;

It can realize time display, countdown display and positive timing display;

The onboard 400mah battery can be used for 13 hours to meet the needs of daily travel and school; the reserved battery space is 28 28 6mm

Onboard 4056 series charging IC and dual power switching circuit for convenient charging;

Among them, R7 is the charging configuration resistor, which can adjust the charging current. The calculation relationship is:

When adjusting R7 to 12K, the charging current is 0.1A, 100ma, which will neither cause too much heat nor charge too slowly.

Battery detection and low battery reminder

You don’t need to solder BAT54C, just connect VB and VCC directly;

welding

When welding, you need to pay attention to the fact that there are several small capacitors in 0402 packages, which may be difficult to see. If possible, it is recommended to use a PTC heating table to assist in welding.

The soldering pad of the button is relatively small and the strength is very tight. You can pile up more tin. Try not to touch the button before the solder paste is completely cooled to avoid falling off the soldering pad. Two of the pieces I made have already fallen off, which is very frustrating.

As you can see, one was ripped off and the thread was temporarily removed. The other one is the reset button, so I won’t care about it for now.

Material purchase

Button: As long as the button is 3*6 in size, the thickness does not matter;

Battery: You can customize it, or you can go to Xixi to buy a 6 yuan children's watch and remove the battery inside and use it.

Take it out just enough to fit.

The battery holder I use is 1.25mm*2P, so you may need to buy the corresponding plastic case and crimping terminals. If you don't have the conditions, you can also buy the corresponding 1.25mm cable, remove the wires inside, and use it with the plastic case.

The rubber shell can be purchased with Xingkun coupons, just choose 1.25mm.

physical object

positive effect

Reserved battery compartment

Charging, power switching, and battery voltage division

negative overall effect

Top view, now the reset button has been ripped off

Demonstration video to be added

software

Key Function

Barely squeezed out 4 IOs from STM8S003 for button detection and interrupt processing

The order of arrangement from left to right is:

PB5--+--PD2--+--PC7--+--PA3

PA3 performs function settings;

PC7 and PD2 are quantity + and quantity minus respectively;

PB5 is a countdown button, single press to enter the countdown;

The code is poorly written, please forgive me.

Development Platform

It is developed using SDUINO made by foreign giants, which is actually an Arduino-like platform.

The code is all written here.

Click here to learn more

If an error is reported, it may be because a driver is missing. You can go to the attachment to download it.