SPRUI33H November 2015 – June 2024 TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1
The SCI uses a programmable frame format. All frames consist of the following:
The frame format for both the transmitter and receiver is programmable through the bits in the SCIGCR1 register. Both receive and transmit data is in nonreturn to zero (NRZ) format, which means that the transmit and receive lines are at logic high when idle. Each frame transmission begins with a start bit, in which the transmitter pulls the SCI line low (logic low). Following the start bit, the frame data is sent and received least significant bit first (LSB).
An address bit is present in each frame if the SCI is configured to be in address-bit mode but is not present in any frame if the SCI is configured for idle-line mode. The format of frames with and without the address bit is illustrated in Figure 27-3.
A parity bit is present in every frame when the PARITY ENA bit is set. The value of the parity bit depends on the number of one bits in the frame and whether odd or even parity has been selected using the PARITY ENA bit. Both examples in Figure 27-3 have parity enabled.
All frames include one stop bit, which is always a high level. This high level at the end of each frame is used to indicate the end of a frame to make sure synchronization between communicating devices. Two stop bits are transmitted, if the STOP bit in SCIGCR1 register is set. The examples shown in Figure 27-3 use one stop bit per frame.