Emulation And Reset Considerations; Mcbsp Emulation Mode; Resetting And Initializing Mcbsp; Mcbsp Emulation Modes Selectable With Free And Soft Bits Of Spcr2 - Texas Instruments Concerto F28M35 Series Technical Reference Manual

Emulation and Reset Considerations

15.10 Emulation and Reset Considerations
This section covers the following topics:
• How to program McBSP response to a breakpoint in the high-level language debugger (see
Section 15.10.1)
• How to reset and initialize the various parts of the McBSP (see

15.10.1 McBSP Emulation Mode

FREE and SOFT are special emulation bits in SPCR2 that determine the state of the McBSP when a
breakpoint is encountered in the high-level language debugger. If FREE = 1, the clock continues to run
upon a software breakpoint and data is still shifted out. When FREE = 1, the SOFT bit is a don't care.
If FREE = 0, the SOFT bit takes effect. If SOFT = 0 when breakpoint occurs, the clock stops immediately,
aborting a transmission. If SOFT = 1 and a breakpoint occurs while transmission is in progress, the
transmission continues until completion of the transfer and then the clock halts. These options are listed in
Table 15-69.
The McBSP receiver functions in a similar fashion. If a mode other than the immediate stop mode (SOFT
= FREE = 0) is chosen, the receiver continues running and an overrun error is possible.
Table 15-69. McBSP Emulation Modes Selectable with FREE and SOFT Bits of SPCR2
FREE SOFT
0 0
0 1
1 0 or 1

15.10.2 Resetting and Initializing McBSP

15.10.2.1 McBSP Pin States: DSP Reset Versus Receiver/Transmitter Reset
Table 15-70 shows the state of McBSP pins when the serial port is reset due to direct receiver or
transmitter reset on the device.
Pin Possible State(s)
Receiver reset (RRST = 0 and GRST = 1)
MDRx
MCLKRx I/O/Z
MFSRx I/O/Z
Transmitter reset (XRST = 0 and GRST = 1)
MDXx O/Z
MCLKXx I/O/Z
MFSXx I/O/Z
(1)
In Possible State(s) column, I = Input, O = Output, Z = High impedance. In the 28x family, at device reset, all I/Os default to
GPIO function and generally as inputs.
1114
C28 Multichannel Buffered Serial Port (McBSP)
McBSP Emulation Mode
Immediate stop mode (reset condition)
The transmitter or receiver stops immediately in response to a breakpoint.
Soft stop mode
When a breakpoint occurs, the transmitter stops after completion of the current word. The receiver is
not affected.
Free run mode
The transmitter and receiver continue to run when a breakpoint occurs.
Table 15-70. Reset State of Each McBSP Pin
State Forced by Device
(1)
Reset
I GPIO-input
GPIO-input
GPIO-input
GPIO Input
GPIO-input
GPIO-input
Copyright © 2012–2019, Texas Instruments Incorporated
Section 15.10.2)
State Forced by
Receiver/Transmitter Reset
Input
Known state if input; MCLKR running if output
Known state if input; FSRP inactive state if output
High impedance
Known state if input; CLKX running if output
Known state if input; FSXP inactive state if output
SPRUH22I – April 2012 – Revised November 2019
Submit Documentation Feedback
www.ti.com