User guide

Si471x-EVB

34 Preliminary Rev. 0.4

6.8.2. Intermediate

In the intermediate section, we will cover the buffers category of sending the RDS data with the Si4711/13, in

particular we will send Group Type 2 (Radio Text) and Group Type 4 (Clock Time).

The following diagram shows a step-by-step procedure to send the buffers data in addition to the General and

Program Service data covered in the basic section.

Figure 30. Intermediate RDS Sending Message Illustration

1. Select the Mix percentage that you want between transmitting the data in Program Service and the data in the Buffers. 100%

means that you will always transmit the PS message regardless of what is contained in the Buffers, while 0% means that

you will always transmit the data in the Buffers regardless of what is contained in the PS. If the buffers are empty though, the

PS messages will be transmitted all the time regardless of the mix percentage.

2. Enter the Radio Text message that will be transmitted. After entering the RT message, click either the "Add to Circular"

button or the "Add to FIFO" button. The RT message will be encoded according to the RDS Group Type 2 rule.

a. Clicking "Add to Circular" button means that you upload the RT message into the Circular Buffer Indicator Window.

Note that the message itself has not been uploaded into the Circular Buffer inside the Si4711/13 until the Clear Buff &

Send is clicked.

b. Clicking "Add to FIFO" means that you upload the RT message into the FIFO Buffer Indicator Window. Note that the

message itself has not been uploaded into the FIFO Buffer inside the Si4711/13 until the Clear Buff & Send is clicked.

3. Enter the size of the FIFO that you want here. The Si4711/13 buffer has a total of 128 blocks, which is shared by the circular

buffer and the FIFO. Therefore the circular buffer size (shown in 3a) will be the remainder of the 128 blocks minus the FIFO

size.

4. Clicking this "Clear Buff & Send" button will upload the message from the Circular Buffer Indicator Window into the Circular

Buffer inside the Si4711/13. Circular buffer holds the message that will be transmitted over and over again. Note that the

messages in the circular buffer will be transmitted only if the PS Mix value is set to anything other than 100%.

5. Clicking the "Add Time" button here will automatically upload the current time into the FIFO. The CT time data is uploaded

into the Si4711 according the RDS Group Type 4 rule.

6. Clicking the "Clear Buff & Send" button will upload the message from the FIFO Buffer Indicator Window into the FIFO Buffer

inside the Si4711/13. FIFO buffer holds the message that will be transmitted only once. A good example of using FIFO buffer

is when you want to send the time data. Time is something that occurs only once, so it will not be beneficial to upload time to

the circular buffer and get transmitted continuously. We will cover how to send time in step #5. Note that the messages in the

FIFO buffer will be transmitted only if the PS Mix value is set to anything other than 100%.