8.3.7.8.13 Frame Slot Mode

This mode is useful only for host nodes. It respects the following rule: each frame slot shall be longer than or equal to tFrame_Maximum.

If the Frame Slot mode is enabled (FSDIS = 0) and a frame transfer has been completed, the TXRDY flag is set again only after tFrame_Maximum delay, from the start of frame. So the host node cannot send a new header if the frame slot duration of the previous frame is inferior to tFrame_Maximum.

If the Frame Slot mode is disabled (FSDIS = 1) and a frame transfer has been completed, the TXRDY flag is set again immediately.

The tFrame_Maximum is calculated as follows:

If the Checksum is sent (CHKDIS = 0):

  • tHeader_Nominal = 34 × tbit
  • tResponse_Nominal = 10 × (NData + 1) × tbit
  • tFrame_Maximum = 1.4 × (tHeader_Nominal + tResponse_Nominal + 1)(1)
  • tFrame_Maximum = 1.4 × (34 + 10 × (DLC + 1 + 1) + 1) × tbit
  • tFrame_Maximum = (77 + 14 × DLC) × tbit

If the Checksum is not sent (CHKDIS = 1):

  • tHeader_Nominal = 34 × tbit
  • tResponse_Nominal = 10 × NData × tbit
  • tFrame_Maximum = 1.4 × (tHeader_Nominal + tResponse_Nominal + 1)(1)
  • tFrame_Maximum = 1.4 × (34 + 10 × (DLC + 1) + 1) × tbit
  • tFrame_Maximum = (63 + 14 × DLC) × tbit
Note:
  1. The term “+1” leads to an integer result for tFrame_Maximum (LIN Specification 1.3).
Figure 8-53. Frame Slot Mode