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 , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-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

4.5.2 RX Tile Logic

The logic for the receive tile is shown in Figure 4-9.

Figure 4-9 CLB RX Tile Logic

The following CLB tile resources are used to implement the CCSI bus receive (RX) functionality:

  • COUNTER0 is used to detect the end of a receive frame.
  • COUNTER1 is used to receive the input data on SCLKX2 falling edges. It is operated in serializer mode.
  • COUNTER2 is used to count SCLKX2 falling edges. It is operated in normal counter mode.
  • The HLC is used to move data from COUNTER1 to the CLB PUSH FIFO. It also generates interrupts to the CPU when four 16-bit words are received and when a CHECK bit error and END of frame condition are detected.
  • FSM0 is used to define and cycle through two states, IDLE and ACTIVE.
  • FSM1 is used to count when four 16-bit words have been received. An event is generated to the HLC when the receive count reaches four.
  • FSM2 is used to generate an END of frame interrupt only when in the ACTIVE state.
  • LUT0 is used to detect a “0” bit corresponding which is used in detecting the START bit as well as the END byte. The LUT0 output can be forced low, effectively disabling receive operations, by clearing the ENABLE_RX input.
  • LUT1 is used to verify the CHECK bit on each 16-bit word. If the CHECK bit does not match the expected state, the LUT1 output will trigger an HLC interrupt.
  • LUT2 is used to keep COUNTER2 in reset when receive operations are disabled (i.e. ENABLE_RX = 0).

FSM0 define two states of operation for the RX tile. The FSM0 state diagram and truth table are shown in Figure 4-10 and Table 4-4.

Figure 4-10 FSM0 State Diagram for RX Tile
Table 4-4 FSM0 Truth Table
S0 E1 (LUT0_OUT) E0 (C0_MATCH1) S0 Next Output (FSM0_OUTPUT)
0 0 0 0 0
0 0 1 0 0
0 1 0 1 0
0 1 1 1 0
1 0 0 1 1
1 0 1 0 1
1 1 0 1 1
1 1 1 0 1

The full logic equations are:

  • S0 = !S1&!S0&E1&!E0 | !S1&!S0&E1&E0 | !S1&S0&!E1&!E0 | !S1&S0&E1&!E0
  • OUTPUT = !S1&S0&!E1&!E0 | !S1&S0&!E1&E0 | !S1&S0&E1&!E0 | !S1&S0&E1&E0

FSM1 is used to trigger an HLC event once four 16-bit words have been received. The FSM1 state diagram and truth table are shown in Figure 4-11 and Table 4-5.

Figure 4-11 FSM1 State Diagram for RX Tile
Table 4-5 FSM1 Truth Table
S1 S0 E1 (FSM0_OUT) E0 (C2_MATCH2) S1 Next S0 Next Output (HLC_INT)
0 0 0 0 0 0 0
0 0 0 1 0 0 0
0 0 1 0 0 0 0
0 0 1 1 0 1 0
0 1 0 0 0 0 0
0 1 0 1 0 0 0
0 1 1 0 0 1 0
0 1 1 1 1 0 0
1 0 0 0 0 0 0
1 0 0 1 0 0 0
1 0 1 0 1 0 0
1 0 1 1 1 1 0
1 1 0 0 0 0 0
1 1 0 1 0 0 0
1 1 1 0 1 1 0
1 1 1 1 0 0 1

The logic equations are:

  • S1 = !S1&S0&E1&E0 | S1&!S0&E1&!E0 | S1&!S0&E1&E0 | S1&S0&E1&!E0
  • S0 = !S1&!S0&E1&E0 | !S1&S0&E1&!E0 | S1&!S0&E1&E0 | S1&S0&E1&!E0
  • OUTPUT = S1&S0&E1&E0