Fast Communications Controllers (FCCs)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
29-18 Freescale Semiconductor

Figure 29-8. Output Delay from RTS Asserted

If CTS is not already asserted when RTS is asserted, the delays to the first bit of data depend on when CTS is asserted. Figure 29-9 shows that the delay between CTS and the data can be approximately 0.5 to 1 bit times or no delay, depending on GFMR[CTSS].

Figure 29-9. Output Delay from CTS Asserted

If it is programmed to envelope the data, CTS must remain asserted during frame transmission or a CTS lost error occurs. The negation of CTS forces RTS high and the transmit data to the idle state. If GFMR[CTSS] = 0, the FCC must sample CTS before a CTS lost is recognized. Otherwise, the negation of CTS immediately causes the CTS lost condition. See Figure29-10.
1. A frame includes opening and closing flags and syncs, if present in the protocol.
TCLK
TXD
Last Bit of Frame DataFirst Bit of Frame Data
Note:
(Output)
RTS
(Output)
CTS
(Input)
1. GFMR[CTSS] = 0. CTSP is a don’t care.
TCLK
TXD
Last Bit of Frame DataFirst Bit Of Frame Data
Note:
CTS Sampled Low
1. GFMR[CTSS] = 1. CTSP is a don’t care.
TCLK
TXD
Last Bit of Frame DataFirst Bit of Frame Data
Note:
(Output)
RTS
(Output)
CTS
(Input)
(Output)
RTS
(Output)
CTS
(Input)