Chapter 6 Multi-channel Buffered Serial Port (McBSP)

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port interrupts. Describe multi-channel operation. Programming the serial port.

Basic Definitions: Bits, Words ? CLK FS Data Data a1 a0 b7 b6 b5 b4 b3 b2 b1 b0 Word Bit “Bit” - one data bit per SP clock period. SP Ctrl (SPCR) Rcv Ctrl (RCR) Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR) Serial Port “Word” or “channel” contains #bits specified by WDLEN1 (8, 12, 16, 20, 24, 32). RWDLEN1 5 7 XWDLEN1

Basic Definitions: Frame? FS w0 w1 w2 w3 w4 w5 w6 w7 Frame Word Data “Frame” - contains one or multiple words FRLEN1 specifies #words per frame (1-128) Serial Port RFRLEN1 8 14 XFRLEN1 7 5 SP Ctrl (SPCR) RWDLEN1 Rcv Ctrl (RCR) Xmt Ctrl (XCR) 7 5 Rate (SRGR) XWDLEN1 Pin Ctrl (PCR)

Basic Definitions - Phase FS Frame Phase 1 Phase 2 Data A B 3 2 1 Note: dual-phase used in Audio Codec97 (AC97) Std Each FRAME can contain only 1 or 2 PHASES (PHASE). Each PHASE can contain different #bits (WDLEN1/2) and #words (FRLEN1/2) . Phase 2 Phase 1 Serial Port PHASE 31 RFRLEN2 RWDLEN2 23 24 21 30 XFRLEN2 XWDLEN2 14 8 7 5 SP Ctrl (SPCR) RFRLEN1 RWDLEN1 Rcv Ctrl (RCR) Xmt Ctrl (XCR) 14 8 7 5 Rate (SRGR) XFRLEN1 XWDLEN1 Pin Ctrl (PCR)

Basic Definitions - Phase FS 8 16 Data 1 2 3 A B Phase 1 Phase 2 Frame Each FRAME can contain 1 or 2 PHASES (PHASE). Each PHASE can contain different #bits (WDLEN1/2) and #words (FRLEN1/2) . From above example some of the bit fields of RCR and XCR can be initialised as shown below. Phase 2 Phase 1 Serial Port 31 30 24 23 21 14 8 7 5 SP Ctrl (SPCR) PHASE RFRLEN2 RWDLEN2 RFRLEN1 RWDLEN1 Rcv Ctrl (RCR) 1 0001 010 0010 000 Xmt Ctrl (XCR) 31 30 24 23 21 14 8 7 5 Rate (SRGR) PHASE XFRLEN2 XWDLEN2 XFRLEN1 XWDLEN1 Pin Ctrl (PCR)

Exercise FS Data Phase 1 Phase 2 Frame 16 20 Data 1 2 3 4 5 A B C Phase 1 Phase 2 Frame Fill in the control values for the example above. RFRLEN2 PHASE RWDLEN2 RFRLEN1 RWDLEN1 5 8 23 24 14 21 30 31 7 XFRLEN2 XWDLEN2 XFRLEN1 XWDLEN1 Phase 2 Phase 1

Definitions - Review CLK Word 1 Word 2 Word 3 FS Phase 1 Phase 2 b1 b2 CLK Word 1 Word 2 Word 3 FS Phase 1 Phase 2 Phase 1 Phase 2 Frame 1 Frame 2 Serial Port RFRLEN1 RWDLEN1 5 8 14 7 XFRLEN1 XWDLEN1 RFRLEN2 RWDLEN2 23 24 21 30 XFRLEN2 XWDLEN2 31 PHASE SP Ctrl (SPCR) Rcv Ctrl (RCR) Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR)

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port interrupts. Describe multi-channel operation. Programming the serial port.

McBSP Block Diagram (Read) CPU DMA P e r i p h e r a l B u s RINT REVT R B D 32 DR CLKR FSR RSR

McBSP Block Diagram (Write) CPU DMA RINT XEVT XINT P e r i p h e r a l B u s DR CLKR FSR RSR R B D R 32 DX XSR D X R CLKX REVT FSX

McBSP Block Diagram (Configuration) Multi-Channel Buffered Serial Port (McBSP) CPU DRR P e r i p h B u s DR RSR RBR DX XSR DXR CLKR Serial Port Control Logic CLKX DMA RCR ? FSR SPCR XCR ? FSX Peripheral Bus

Serial Port - Basic Operation Multi-Channel Buffered Serial Port (McBSP) CPU DMA DRR P e r i p h B u s DR RSR RBR DX CLKX FSX XSR DXR CLKR Peripheral Bus Serial Port Control Logic SPCR RCR XCR PCR SRGR FSR “TRANSMIT” “RECEIVE”

McBSP Registers (1) Receive Transmit Control RSR Receive Shift Reg RBR Receive Buffer Reg DRR Data Receive Reg Receive XSR Transmit Shift Reg DXR Data Transmit Reg Transmit SPCR Serial Port Control Reg RCR Receive Control Reg XCR Transmit Control Reg Control

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port interrupts. Describe multi-channel operation. Programming the serial port.

Configure CLK and FS as inputs or outputs Multi-Channel Buffered Serial Port (McBSP) CLKR Serial Port Control Logic CLKX RCR SRGR FSR SPCR FSX XCR PCR FSR, FSX, CLKR and CLKX can be configured either as inputs or outputs, depending on the application.

Configure CLK and FS as inputs or outputs Multi-Channel Buffered Serial Port (McBSP) CLKR Serial Port Control Logic CLKX RCR SRGR FSR SPCR FSX XCR PCR CLK/FS Mode 0: Input 1: Output SP Ctrl (SPCR) Rcv Ctrl (RCR) Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR) Serial Port 11 10 9 8 FSXM FSRM CLKXM CLKRM

Generating CLK and FS as output FSR FSX CLKR CLKX CLK/FS Mode 0: Input 1: Output SP Ctrl (SPCR) Rcv Ctrl (RCR) Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR) Serial Port CLKRM FSRM 10 FSXM 11 CLKXM 8 9

Generating the CLK as output Sample Rate Generator (SRGR) CLKOUT1 CLKS CLKGDV CLKG FSR FSX CLKR CLKX CLKSM CLKSM - selects clock src (CLKOUT1 or CLKS) CLKGDV - divide down (1-255) CLKG = (input clock) / (1 + CLKGDV) Max transfer rate = CLKG = 150 MHz/2 = 75 Mb/s Serial Port SP Ctrl (SPCR) Rcv Ctrl (RCR) Xmt Ctrl (XCR) CLKSM 29 CLKGDV 7 Rate (SRGR) Pin Ctrl (PCR)

Generating the FS as output ‘C6000 Sample Rate Generator (SRGR) CLKSM CLKOUT1 CLKS CLKGDV FSR FSX CLKR CLKX FPER FSG CLKG FSGM: 0 - FS gen’d on every DXR XSR copy 1 - FS gen’d by FSG FPER: frame sync period (12 bits) Serial Port SP Ctrl (SPCR) FWID: frame sync pulse width (8 bits) Rcv Ctrl (RCR) Xmt Ctrl (XCR) 29 28 27 16 15 8 7 Rate (SRGR) CLKSM FSGM FPER FWID CLKGDV Pin Ctrl (PCR)

McBSP Registers (2) Receive Transmit Control RSR Receive Shift Reg RBR Receive Buffer Reg DRR Data Receive Reg Receive XSR Transmit Shift Reg DXR Data Transmit Reg Transmit SPCR Serial Port Control Reg RCR Receive Control Reg XCR Transmit Control Reg SRGR Sample Rate Generator Control

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port interrupts. Describe multi-channel operation. Programming the serial port.

Configure CLK and FS pin polarity Multi-Channel Buffered Serial Port (McBSP) CLKR Serial Port Control Logic CLKX RCR SRGR FSR SPCR FSX XCR PCR CLK/FS Polarity 0: Falling edge 1: Rising Edge SP Ctrl (SPCR) Rcv Ctrl (RCR) Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR) Serial Port 3 2 1 FSXP FSRP CLKXP CLKRP

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port status and interrupts. Describe multi-channel operation. Programming the serial port.

RRDY/XRDY Status and Interrupts RRDY/XRDY displays the “status” of the read and transmit ports: 0: not ready. 1: ready to read/write. RBR DRR CPU RINT XINT RRDY=1 “Ready to Read” EDMA Sync There are 3 methods for detecting if data is ready: Poll SPCR bits via s/w. Config CPU ints (RINT/XINT). Program DMA sync events. XSR DXR XRDY=1 “Ready to Write” Serial Port SP Ctrl (SPCR) 17 1 Rcv Ctrl (RCR) XRDY RRDY Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR)

Other sources of Interrupts (R/XINT) RRDY (RINTM=00b) End of Block (RCV) (RINTM=01) New FSR (frame begin) (RINTM=10b) Receive Sync Error (RINTM=11b) XRDY (XINTM=00b) End of Block (XMT) (XINTM=01b) New FSX (frame begin) (XINTM=10b) Transmit Sync Error (XINTM=11b) “Trigger Event” CPU RINT XINT Serial Port SP Ctrl (SPCR) 21 20 17 5 4 1 Rcv Ctrl (RCR) XINTM XRDY RINTM RRDY Xmt Ctrl (XCR) Rate (SRGR) Pin Ctrl (PCR)

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port status and interrupts. Describe multi-channel operation. Programming the serial port.

Multi-Channel operation DR/X Ch0 Ch1 . . . Ch31 Ch0 Ch1 . . . Ch31 FSR/X How do you enable/disable each channel?

Multi-Channel operation DR/X Ch0 Ch1 . . . Ch31 Ch0 Ch1 . . . Ch31 FSR/X You can enable or disable any channel. RCER/XCER Enable Bits Enable [1] Disable [0] 31 Master (MCR) Rcv En (RCER) Xmt En (XCER) Multi-Channel RCER … 1 1 1 31 XCER

Multi-channel example F r a m e 4 3 2 1 Frame 3 1 4 3 2 Frame 2 1 Frame 1 4 3 2 3 1 3 1 M c B S P Memory Allows multiple channels (words) to be independently selected for transmit and receive. 1 3 .

Multi-channel and EDMA combination used for channel sorting Memory 4 3 2 1 Frame 3 . Frame 1 Frame 2 F r a m e M c B S P E D A EDMA’s can sort each channel into separate buffers!

EDMA Channel Sorting 4 3 2 1 . Memory Frame 3 Frame 1 Frame 2 F r a m B S P E D A EDMA’s flexible (indexed) addressing allows it to sort each channel into separate buffers! How do you select channels? ...

Enable/Disable Channels RCER / XCER registers allow you to enable or disable only 32-channels. So how does the C6000 supports 128 channels? 31 RCER XCER 1 … Master (MCR) Rcv En (RCER) Xmt En (XCER) Multi-Channel

128 Channels! 0-15 16-31 32-47 48-63 64-79 80-95 96-111 112-127 Channels A B To be able to support 128 channels the following applies: Channels are broken into BLOCK’s (16 contiguous channels). Up to 32 channels (2 BLOCK’s) can be enabled at any one time. Channels are enabled via _CER registers and _BLK bits in MCR. After 16 channels, McBSP issues END_OF_BLOCK interrupt. CPU ISR re-programs RCER (or XCER) for channels 32-47 and so on. Interrupt A15-0 B15-0 15 16 Master (MCR) Rcv En (RCER) Xmt En (XCER) Multi-Channel 31 RCER XCER

McBSP Registers (3) Receive Transmit Control RSR Receive Shift Reg RBR Receive Buffer Reg DRR Data Receive Reg Receive XSR Transmit Shift Reg DXR Data Transmit Reg Transmit SPCR Serial Port Control Reg RCR Receive Control Reg XCR Transmit Control Reg SRGR Sample Rate Generator PCR Pin Control Reg Control MCR Multi-Channel Ctrl Reg RCER Rcv Channel Enable Reg XCER Xmit Channel Enable Reg

Objectives Definition of Terms: Bit, word or channel, frame and phase. Understand basic serial port operation. Understand clock generation. Pin polarity. Serial port status and interrupts. Describe multi-channel operation. Programming the serial port.

Programming the Serial Port There are three methods available for programming the serial port: 1. Writing directly to the serial port registers. 2. Using the Chip Support Library (CSL). 3. Graphically using the DSP/BIOS GUI configuration tool.

Programming the Serial Port - Direct (A) Writing directly to the serial port registers: Although this method is straight forward, it relies on a good understanding of the serial port functionality. This method can be tedious and is prone to errors. #include <c6211dsk.h> void mcbsp0_init() { *(unsigned volatile int *)McBSP0_SPCR = 0; *(unsigned volatile int *)McBSP0_PCR = 0; *(unsigned volatile int *)McBSP0_RCR = 0x10040; *(unsigned volatile int *)McBSP0_XCR = 0x10040; *(unsigned volatile int *)McBSP0_DXR = 0; *(unsigned volatile int *)McBSP0_SPCR = 0x12001; }

Programming the Serial Port - CSL (1/4) (B) Using the Chip Support Library: The CSL provides a C language interface for configuring and controlling the on-chip peripherals, in this case the Serial Ports. The library is modular with each module corresponding to a specific peripheral. This has the advantage of reducing the code size. Some modules rely on other modules also being included, for example the IRQ module is required when using the EDMA module.

Programming the Serial Port - CSL (1/4) CSL programming procedure: (1) Create handles for the serial ports: (2) Open the serial port: MCBSP_Handle hMcbsp; hMcbsp = MCBSP_open(MCBSP_DEV1, MCBSP_OPEN_RESET);

Programming the Serial Port - CSL (2/4) CSL programming procedure: (3) Create a configuration structure for serial port: \Links\McBSP_Config_Struct.pdf

Programming the Serial Port - CSL (3/4) CSL programming procedure (cont): (4) Configure the serial port: (5) Close the Serial Port after use: MCBSP_config(hMcbsp,&ConfigLoopback); MCBSP_close(hMcbsp);

Programming the Serial Port - CSL (4/4) Practical example on DSP Code 6711 Project name: mcbsp_dynamiccfg.pjt Location: \Code\Chapter 06 - McBSP\Dynamic_CSL_Config\

Programming the Serial Port using the DSP/BIOS GUI (C) DSP/BIOS GUI Interface: With this method the configuration structure is created graphically and the setup code is generated automatically.

Programming the Serial Port using the DSP/BIOS GUI Procedure: (1) Create a configuration using the MCBSP Configuration manager (eg. mcbspCfg0).

Programming the Serial Port using the DSP/BIOS GUI Procedure: (2) Right click on mcbspCfg0 and select “Properties”, see figures below, and then select “Advanced” and fill all parameters as shown below:

Programming the Serial Port using the DSP/BIOS GUI Procedure: (3) Select the serial port you would like to use from the MCBSP Resource manager (eg. Mcbsp_Port1). Right click and select properties. Select the mcbspCfg0 configuration just created.

Programming the Serial Port using the DSP/BIOS GUI Procedure: (4) A file is then generated that contains the configuration code. The file generated for this example is shown on the next slide.

Programming the Serial Port using the DSP/BIOS GUI /* Do *not* directly modify this file. It was */ /* generated by the Configuration Tool; any */ /* changes risk being overwritten. */ /* INPUT mcbsp1.cdb */ /* Include Header File */ #include "mcbsp1cfg.h" /* Config Structures */ MCBSP_Config mcbspCfg0 = { 0x00008000, /* Serial Port Control Reg. (SPCR) */ 0x000000A0, /* Receiver Control Reg. (RCR) */ 0x000000A0, /* Transmitter Control Reg. (XCR) */ 0x203F1F0F, /* Sample-Rate Generator Reg. (SRGR) */ 0x00000000, /* Multichannel Control Reg. (MCR) */ 0x00000000, /* Receiver Channel Enable(RCER) */ 0x00000000, /* Transmitter Channel Enable(XCER) */ 0x00000A00 /* Pin Control Reg. (PCR) */ }; /* Handles */ MCBSP_Handle hMcbsp1; /* * ======== CSL_cfgInit() ======== */ void CSL_cfgInit() { hMcbsp1 = MCBSP_open(MCBSP_DEV1, MCBSP_OPEN_RESET); MCBSP_config(hMcbsp1, &mcbspCfg0); }

Programming the Serial Port using the DSP/BIOS GUI Few remarks: (1) Notice that values in the code generated are the same as the values inserted using the GUI interface. /* Do *not* directly modify this file. It was */ /* Config Structures */ MCBSP_Config mcbspCfg0 = { 0x00008000, /* Serial Port Control Reg. (SPCR) */ 0x000000A0, /* Receiver Control Reg. (RCR) */ 0x000000A0, /* Transmitter Control Reg. (XCR) */ 0x203F1F0F, /* Sample-Rate Generator Reg. (SRGR) */ 0x00000000, /* Multichannel Control Reg. (MCR) */ 0x00000000, /* Receiver Channel Enable(RCER) */ 0x00000000, /* Transmitter Channel Enable(XCER) */ 0x00000A00 /* Pin Control Reg. (PCR) */ };

Programming the Serial Port using the DSP/BIOS GUI Few remarks: (2) Do not forget to close the serial port after use. (3) To visualise the output of the logprintf () function make sure that the Message Log window is open (DSP/BIOS > Message Log).

Programming the Serial Port - CSL (4/4) Practical example Project name: mcbsp_staticcfg.pjt Location: \Code\Chapter 06 - McBSP\Static_CSL_Config\ Extra Topic: Digital Loopback

Chapter 6 Multi-channel Buffered Serial Port (McBSP) - End -

Digital Loopback (DLB) McBSP DR CLKR FSR RCV FSX CLKX DX XMT Allows testing of the Serial Port code without the need of an external device. Digital Loopback internally connects the rcv/xmt ports together as shown. No hardware (pin connections) necessary. Interrupts are generated as normal (as programmed).

Digital Loopback (DLB) You can set the digital loop back by setting a bit in the SPCR or graphically using the GUI interface as shown: SPCR 31 15 DLB