[SOLVED] Unknow pin on a popular DS1307 board

Projects General Guidance
1

I wonder if someone can shed some light over this "DS" pin on a popular DS1307 breakout board:

Take a look at the pictures. The DS pin seems to be connected to an unpopulated pad (resistor?) that is connected to a transistor-looking pattern. Does anyone know what this pin does?

Thanks.

2

Take a look at the pictures.

It said:-

Access Denied
You don't have permission to access "http://www.banggood.com/I2C-RTC-DS1307-AT24C32-Real-Time-Clock-Module-For-AVR-ARM-PIC-SMD-p-89311.html" on this server.

Reference #18.a1ff4317.1469654009.530137a9

3

The DS pin seems to be connected to an unpopulated pad

I'll bet the DS pin does nothing.

4

Hi,
Sainsmart have the same device.

It has a documents file.

Tom... :slight_smile:

5

I just looked through all of those documents and couldn't find an answer.

The letters "ds" are used in the demo example...

#include <OneWire.h>
#include <WProgram.h>
/* DS18S20 Temperature chip i/o */
#include <Wire.h>
#include <DS1307.h>

OneWire ds(3); // on pin 3
byte Tdata[12];
int rtc[7];
//int deviceaddress = 0x50;
int deviceaddress = 0x52;
int addr=0; //first address
int lastTime;
byte saveDate[6];
boolean full=false;
int ledPin = 13;
int outpin=3;
int val = 0; // variable to store the read value

There's more to that code I can post if someone thinks it might help, but I don't even know if the "ds" in the code and the "ds" on the board are related. I simply don't have enough experience with coding.

6

Trace out the circuit - what is the other end of that resistor-like thing, and the other pins on the transistor-like thing connected to? That - and the datasheet for the parts that are on the board - will probably point you in the right direction.

7

Some of the modules were designed to have a DS18B20/DS18S20 chip on board, similar to the added eeprom. The DS is the one wire pin connection. See the empty three pin area on this image.

8

Great! Ds18 series one wire temperature probe. Makes sense. Thanks.

9

Here's a schematic:-
DS1307_24_C32.jpg

10

Thanks again! All EEPROM address pins are grounded. Looks like 3K3 pullup for I2C. I hope after adding this one and an ADS1115 breakout (10K pullup) and a 10DEF board (unknown pullup), the I2C pullup won't be too small :slight_smile:

11

liudr:
I hope after adding this one and an ADS1115 breakout (10K pullup) and a 10DEF board (unknown pullup), the I2C pullup won't be too small :slight_smile:

Yeah. I hate the fact that so many I2C-based boards have on-board pullups. :frowning: