SPRAD62 February   2023 TMS320F280023C , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038C-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DK-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Serial Port Design Methodology
    1. 2.1 Step 1: Understand Design Requirements
    2. 2.2 Step 2: Identify Required Inputs to the CLB Tile
      1. 2.2.1 GPIO Input Qualification
      2. 2.2.2 CLB Input Settings
    3. 2.3 Step 3: Identify Required Outputs from CLB Logic
      1. 2.3.1 Synchronizing Outputs Signals
      2. 2.3.2 Output Signal Conditioning
    4. 2.4 Step 4: Design the CLB Logic
      1. 2.4.1 Resource Allocation
      2. 2.4.2 Exchanging Data Between CLB FIFOs and MCU RAM
      3. 2.4.3 CLB Logic Status and Trigger Flags
        1. 2.4.3.1 Status/Flag Bits
        2. 2.4.3.2 Trigger Bits
    5. 2.5 Step 5: Simulate the Logic Design
    6. 2.6 Step 6: Test the CLB Logic
  5. 3Example A: Using the CLB to Input and Output a TDM Stream in Audio Applications
    1. 3.1 Example Overview
    2. 3.2 Step 1: Understand Design Requirements
    3. 3.3 Step 2: Identify Required Inputs to the CLB Tile
    4. 3.4 Step 3: Identify Required Outputs from CLB Logic
    5. 3.5 Step 4: Design the CLB Logic
      1. 3.5.1 Resource Allocation
      2. 3.5.2 TDM Word Counter
      3. 3.5.3 FSYNC and DATA1 Output Synchronization
    6. 3.6 Step 5: Simulate the Logic Design
    7. 3.7 Step 6: Test the CLB Logic
      1. 3.7.1 Hardware Setup and Connections
      2. 3.7.2 Software Setup
      3. 3.7.3 Testing Output Setup and Hold Times
      4. 3.7.4 Testing Data Integrity
  6. 4Example B: Using the CLB to Implement a Custom Communication Bus for LED Driver in Lighting Applications
    1. 4.1 Example Overview
    2. 4.2 Step 1: Understand Design Requirements
    3. 4.3 Step 2: Identify Required Inputs to the CLB Tile
    4. 4.4 Step 3: Identify Required Outputs From CLB Logic
    5. 4.5 Step 4: Design the CLB Logic
      1. 4.5.1 TX Tile Logic
      2. 4.5.2 RX Tile Logic
      3. 4.5.3 Data Clocking
    6. 4.6 Step 5: Simulate the Logic Design
    7. 4.7 Step 6: Test the CLB Logic
      1. 4.7.1 Hardware Setup and Connections
      2. 4.7.2 Software Setup
      3. 4.7.3 Testing Output Setup and Hold Times
  7. 5References

4.5.3 Data Clocking

The clocks needed for the CCSI bus communication are generated using an on-chip PWM. The PWMnA output generates a PWM_SCLKX2 clock running at double the target SCLK frequency, while the PWMnB output is generates a PWM_SCLK clock at the required SCLK frequency.

The TX and RX CLB tiles always transmit and receive data using the PWM_SCLKX2 clock. Only PWM_SCLK is eventually driven to the LED drivers in the system.

Dual- or single-clock edge data transmission and reception is achieved by configuring the source of the PWM_SCLK input to the TX tile. When single-clock edge transmission and reception is required, for example, when using the LP5891-Q1 LED driver, the TX input tile configuration can be modified to drive the PWMnA output to both PWM_SCLK and PWM_SCLKX2 inputs, see Figure 4-12. The PWMnB output can be left unconnected from the CLB tiles.

Figure 4-12 Single-Clock Edge Data Transmission and Reception Clock Configuration

Dual-clock edge data transmit/receive allows for the transmission and reception on both edges of the clock, see Figure 4-13.

Figure 4-13 Dual-Clock Edge Data Transmit/Receive Using PWM_SCLKX2

When dual-clock edge transmission and reception is required, the TX input tile configuration can be modified to drive the PWMnA output to the PWM_SCLKX2 input and the PWMnB output to the PWM_SCLK input, see Figure 4-14.

Figure 4-14 Dual-Clock Edge Data Transmission and Reception Clock Configuration

To mitigate timing delays introduced by the CLB logic, both of the PWM clock inputs are passed through the TX CLB logic.