4513_03 Datasheet, PDF (57/210 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCOMPUTER

HARDWARE
FUNCTION BLOCK OPERATIONS
(8) A-D conversion timing chart
Figure 27 shows the A-D conversion timing chart.
ADST instruction
A-D conversion
completion flag (ADF)
DAC operation signal
62 machine cycles
Fig. 27 A-D conversion timing chart
(9) How to use A-D conversion
How to use A-D conversion is explained using as example in which
the analog input from P40/AIN4 pin is A-D converted, and the high-
order 4 bits of the converted data are stored in address M(Z, X, Y)
= (0, 0, 0), the middle-order 4 bits in address M(Z, X, Y) = (0, 0, 1),
and the low-order 2 bits in address M(Z, X, Y) = (0, 0, 2) of RAM.
The A-D interrupt is not used in this example.
ΠAfter selecting the AIN4 pin function with the bit 0 of the register
Q2, select AIN4 pin and A-D conversion mode with the register
Q1 (refer to Figure 28).
 Execute the ADST instruction and start A-D conversion.
Ž Examine the state of ADF flag with the SNZAD instruction to de-
termine the end of A-D conversion.
 Transfer the low-order 2 bits of converted data to the high-order
2 bits of register A (TALA instruction).
 Transfer the contents of register A to M (Z, X, Y) = (0, 0, 2).
‘ Transfer the high-order 8 bits of converted data to registers A
and B (TABAD instruction).
’ Transfer the contents of register A to M (Z, X, Y) = (0, 0, 1).
“ Transfer the contents of register B to register A, and then, store
into M(Z, X, Y) = (0, 0, 0).
(Bit 3)
(Bit 0)
0 ! ! 1 A-D control register Q2
AIN4 function selected
A-D conversion mode
(Bit 3)
!1
(Bit 0)
0 0 _{A-D control register Q1}
AIN4 pin selected
! : Set an arbitrary value
Fig. 28 Setting registers
1-44
4513/4514 Group User’s Manual