How to transmit I2C data to the slave IC?

Here is the example for you about sending I2C data into tuner as a slave.

 

Table below are write data format of I2C into the IC.

Figure 1. Write data format

Address byte (ADB) à address slave IC byte (write/read command)

Divider byte 1 dan 2 (DB1,2) à switching broadcasting frequency

Control byte 1 dan 2 (CB1,2) à slave IC setting for many think (see datasheet)

Band switch byte (BB) à band switching (VHF-L, VHF-H, UHF), charge pump, etc.

A à Acknowledge (information signal to the master for completing data receive and ready to receive next data)

 

Example:

In IC SN761668 (Texas Instrument)

Address byte : 11000010 (C2h) write command

Divider byte 1 : 00001011 (0Bh) freq. 474MHz, IF 36.167MHz

Divider byte 2 : 11110101 (F5h) Step size: 166.67kHz

Control byte 1 : 10010000 (90h)

Band Switch byte  : 11011000 (D8h) UHF band.

Control byte 2 : 11000010 (C2h)

 

Source: http://www.alldatasheet.net/datasheet-pdf/pdf/168704/TI/SN761668.html

I2C data are going to transmit have to be follow the sequence as a table above. There are different format in each slave IC type.

 

The communication data as like below approximation:



Figure 2. I2C data (example)

For the master IC program is up to you.

 

Need your feedback for wrong data communications.

What is I2C (Inter Integrated Circuit) ??

What is I2C which is mean Inter Integrated Circuit???. The meaning is a circuit integrate each other. I2C communication as minimum two devices, master and slave. An one of circuit integration, it's only one of master device, but the slave are can be more than two devices.

Many application that using I2C communication in a system. Connection data is only using two communication lines, it’s SDA and SCL. SDA is Serial Data Address and SCL is Serial Clock. Both lines is continuously each other.

Figure 1. I2C configuration

I try to explain as simply words of how I2C is working. Many kinds of explanation in the website. But it’s still makes confuse for they had never know what I2C is, where it used. I hope you can a bit understand how I2C data is transmit. My explanation is on I2C application in television tuner device.

IC Master is used to transmit information data of frequency and IC slave setting. And the IC slave is used to control the devices are connected. As like switching television channel broadcast, band frequency (VHF/ UHF) and anything else of IC setting needed.

 

A number of data are send to IC slave is 6 byte, 1 byte for Address byte, 2 bytes for frequency switching, 2 bytes for IC setting, 1 byte for switching band. It’s different in each device. You have to be read datasheet IC at first before controlling tha slaves.

As described by many sites, normal condition of SDA and SCL is high, it was supported by pull up circuit to make high logic in idle condition IC master.

 

 



Figure 2. Start and Stop condition

How to make start and stop signal condition? Here is the beginning.

Start signal is used to start sending data to the slave. Done with makes “0” on SDA at the SCL in “1” condition. And Stop signal is used for finish sending data to the slave. Can be done with makes “1” on SDA at the SCL in  “1” condition. 

 

Another I2C signal is acknowledge signal as we know as ACK. This signal is on the last of  1 byte data sending from master. About who is the sender of this signal? After I browse in search engine world, the sender is IC slave. It mean after 1 byte (8 bit) data are received.



Figure 3. ACK and NACK signal condition



I2C data has a procedure are required set by international standardization.

As below:

Data transferred in idle condition data bus, another words is not busy line bus. In a data transfer process, Data condition is have to be stable on SDA signal as long as SCL condition is high “1”. Changing condition “1” to “0” or opposite on SDA is only can be changed as long as SCL in “0” condition. If  changing condition in SDA at the SCL is high “1”, so it’s assume as Start or Stop signal.  

Figure 4. I2C bus data condition

SDA is send data to slave in every clock received.

 

Example of sending I2C data is going to describe In next post.

The application is for Television tuner IC.

What is Phase Locked Loop (PLL)??

Many kind of information of PLL (Phase Locked Loop) which is mean close circuit with locked by phase. Sometimes it’s a bit difficult of the meaning consume for non expert like us. I’d just understand what PLL is, how to work and application in the circuit after many years later. It cause of my brain is not really good for low accepting maybe. J

 

I try to share for a simple explanation about PLL. In order to you get a bit comprehension about  how and what for the PLL purpose. The block as like below.

 

Figure 1. PLL Block Diagram

X-Tal:

Works as signal reference for signal detector, usually use X-tal as reference frequency.

 

Reference Divider:

Divide oscillation reference from X-tal. The purpose is for divide oscillation signal with 128 / 80 / 64 / 50 / 28 / 24 divider. This block can be fixed to the one of the divider in the circuit.

 

Phase Detector:

This block would detect of different phase between two input and going to supply signal to Charge pump block. Phase detector output is going to 0 if the reference signal is same as feedback signal.

 

Charge Pump:

This block is working as like DC/DC converter. It works for increase and decrease signal level are received from phase detector. Signal produced are still in frequency signal.

 

LPF:

LPF (Low pass filter) is working to make a limitation of signal input. More high frequency received from charge pump, the output will down in level. And it’s use also for changing signal into direct current to the VCO. Because of VCO requirement is DC voltage.

 

VCO:

VCO is Voltage Controlled Oscillator. It means this block are works to produce frequency which is controlled by input voltage. Output frequency is proportional with the input.

 

Programmable divider:

The function of programmable divider is divide of frequency feedback from VCO which is continued to phase detector block. Divider system is programmable via data line as we call I2C. For more explanation of I2C, it would be discuss at next time. The purpose is  divider system can make output VCO is suit to the frequency as we want.

 

There are a very simple explanation about how PLL’s working. PLL block as usually used in tuning frequency in tuner system television.