Enhanced Synchronous Serial Interface (ESSI)
ESSI Programming Model
MOTOROLA
DSP56309UM/D 7-11
7.4.1
ESSI Control Register A (CRA)
The ESSI control register A (CRA) is one of two 24-bit, read/write control registers used
to direct the operation of the ESSI. The CRA controls the ESSI clock generator bit and
frame sync rates, word length, and number of words per frame for the serial data. The
CRA control bits are described in the following paragraphs; see also
7.4.1.1
CRA Prescale Modulus Select PM[7:0] Bits 7Ð0
The PM[7:0] bits specify the divide ratio of the prescale divider in the ESSI clock
generator. A divide ratio from 1 to 256 (PM = $0 to $FF) can be selected. The bit clock
output is available at the transmit clock signal (SCK) and/or the receive clock (SC0)
signal of the DSP. The bit clock output is also available internally for use as the bit clock
to shift the transmit and receive shift registers. The ESSI clock generator functional
diagram is shown in
core
is the DSP56309 core clock frequency (the same
frequency as the CLKOUT signal, when that signal is enabled). Careful choice of the
crystal oscillator frequency and the prescaler modulus allows generation of the
industry-standard codec master clock frequencies of 2.048 MHz, 1.544 MHz, and
1.536 MHz. Both the hardware RESET signal and the software RESET instruction clear
PM[7:0].
7.4.1.2
CRA Reserved Bits 8Ð10
These bits are reserved. They are read as 0 and should be written with 0.
7.4.1.3
CRA Prescaler Range (PSR) Bit 11
The PSR controls a fixed divide-by-eight prescaler in series with the variable prescaler.
This bit is used to extend the range of the prescaler for those cases where a slower bit
clock is desired. When PSR is set, the fixed prescaler is bypassed. When PSR is cleared,
the fixed divide-by-eight prescaler is operational; see
Note:
This definition is reversed from that of the 560xx SSI.
The maximum allowed internally generated bit clock frequency is the internal DSP56309
clock frequency divided by 4; the minimum possible internally generated bit clock
frequency is the DSP56309 internal clock frequency divided by 4096. Both the hardware
RESET signal and the software RESET instruction clear PSR.
Summary of Contents for DSP56309
Page 25: ...xxii DSP56309UM D MOTOROLA Figure D 25 Port E Registers PCRE PRRE PDRE D 39 ...
Page 30: ...MOTOROLA DSP56309UM D 1 1 SECTION 1 DSP56309 OVERVIEW ...
Page 47: ...1 18 DSP56309UM D MOTOROLA DSP56309 Overview DSP56309 Architecture Overview ...
Page 48: ...MOTOROLA DSP56309UM D 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Page 85: ...2 38 DSP56309UM D MOTOROLA Signal Connection Descriptions OnCE JTAG Interface ...
Page 86: ...MOTOROLA DSP56309UM D 3 1 SECTION 3 MEMORY CONFIGURATION ...
Page 104: ...MOTOROLA DSP56309UM D 4 1 SECTION 4 CORE CONFIGURATION ...
Page 124: ...MOTOROLA DSP56309UM D 5 1 SECTION 5 GENERAL PURPOSE I O ...
Page 125: ...5 2 DSP56309UM D MOTOROLA General Purpose I O 5 1 INTRODUCTION 5 3 5 2 PROGRAMMING MODEL 5 3 ...
Page 128: ...MOTOROLA DSP56309UM D 6 1 SECTION 6 HOST INTERFACE HI08 ...
Page 166: ...MOTOROLA DSP56309UM D 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Page 212: ...MOTOROLA DSP56309UM D 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Page 241: ...8 30 DSP56309UM D MOTOROLA Serial Communication Interface SCI GPIO Signals and Registers ...
Page 242: ...MOTOROLA DSP56309UM D 9 1 SECTION 9 TRIPLE TIMER MODULE ...
Page 269: ...9 28 DSP56309UM D MOTOROLA Triple Timer Module Timer Operational Modes ...
Page 270: ...MOTOROLA DSP56309UM D 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Page 302: ...MOTOROLA DSP56309UM D 11 1 SECTION 11 JTAG PORT ...
Page 369: ...C 22 DSP56309UM D MOTOROLA DSP56309 BSDL Listing ...
Page 370: ...MOTOROLA DSP56309UM D D 1 APPENDIX D PROGRAMMING REFERENCE ...
Page 405: ......
Page 409: ......