414
•
Bit 7 (Trigger Enable (TRGE)): TRGE selects whether or not to start A/D conversion when an
external trigger is input.
Bit 7 (TRGE)
Description
0
When an external trigger is input, A/D conversion does not start
(Initial value)
1
A/D conversion starts at the falling edge of an input signal from the external
trigger pin (
ADTRG
).
•
Bits 6–0 (Reserved): These bits are always read as 1. The write value should always be 1.
14.3
CPU Interface
The A/D data registers (ADDRA–ADDRD) are 16-bit registers, but they are connected to the CPU
by an 8-bit data bus. Therefore, the upper byte of each register can be read directly, but the lower
byte is accessed through an 8-bit temporary register (TEMP).
When the CPU reads the upper byte of an A/D data register, the upper byte is transferred to the
CPU and the lower byte to TEMP. When the lower byte is accessed, the value in TEMP is
transferred to the CPU.
A program should first read the upper byte, then the lower byte of the A/D data register. This can
be performed by reading ADDR from the upper byte end using a word transfer instruction
(MOV.W, etc.). Reading only the upper byte would assure the CPU of obtaining consistent data. If
the program reads only the lower byte, however, consistent data will not be guaranteed.
Figure 14.2 shows the data flow during access to A/D data registers.
Summary of Contents for HD6417032
Page 21: ......
Page 35: ...xiv ...
Page 85: ...50 ...
Page 101: ...66 ...
Page 129: ...94 ...
Page 135: ...100 ...
Page 343: ...308 ...
Page 369: ...334 ...
Page 383: ...348 ...
Page 475: ...440 ...
Page 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
Page 578: ...543 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 62 Self Refresh ...
Page 689: ...654 ...