Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - DA converter (DAC) SOIC 16 N

TLV5614

2.7-V TO 5.5-V 12-BIT 3-µS QUADRUPLE DIGITAL-TO-ANALOG CONVERTERS

WITH POWER DOWN

SLAS188B – SEPTEMBER 1998 – REVISED APRIL 2003

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

APPLICATION INFORMATION

;–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

; Processor: TMS320C203 runnning at 40 MHz

;

; Description:

;

; This program generates a differential in–phase (sine) on (OUTA–OUTB) and it’s

; quadrature (cosine) as a differential signal on (OUTC–OUTD).

;

; The DAC codes for the signal samples are stored as a table of 64 12–bit values,

; describing 2 periods of a sine function. A rolling pointer is used to address the

; table location in the first period of this waveform, from which the DAC A samples

; are read. The samples for the other 3 DACs are read at an offset to this rolling

; pointer:

; DAC Function Offset from rolling pointer

; A sine 0

; B inverse sine 16

; C cosine 8

; D inverse cosine24

;

; The on–chip timer is used to generate interrupts at a fixed rate. The interrupt

; service routine first pulses LDAC low to update all DACs simultaneously

; with the values which were written to them in the previous interrupt. Then all

; 4 DAC values are fetched and written out through the synchronous serial interface

; Finally, the rolling pointer is incremented to address the next sample, ready for

; the next interrupt.

;

;  1998, Texas Instruments Inc.

;–––––––––––––––––––––––––––––– I/O and memory mapped regs –––––––––––––––––––––––––––––

.include ”regs.asm”

;–––––––jump vectors –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

.ps 0h

b start

b int1

b int23

b timer_isr;

––––––––––– variables –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

temp .equ 0060h

r_ptr .equ 0061h

iosr_stat .equ 0062h

DACa_ptr .equ 0063h

DACb_ptr .equ 0064h

DACc_ptr .equ 0065h

DACd_ptr .equ 0066h

;–––––––––––constants––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––

; DAC control bits to be OR’ed onto data

; all fast mode

DACa_control .equ 01000h

DACb_control .equ 05000h

DACc_control .equ 09000h

DACd_control .equ 0d000h

;––––––––––– tables ––––––––––––––––––––––––––––––––

.ds 02000h

sinevals

.word 00800h

.word 0097Ch

.word 00AE9h

.word 00C3Ah

.word 00D61h

.word 00E53h

.word 00F07h

.word 00F76h

.word 00F9Ch

.word 00F76h

.word 00F07h

.word 00E53h