A/D Conversion Start By External Trigger Input; Interrupts And Dma Transfer Requests - Hitachi SH7032 Hardware Manual

Table 14.4 A/D Conversion Time (Single Mode)
Item
A/D start delay
Input sampling time
Total A/D conversion time
Note: Values are the number of states (tcyc).
14.4.4

A/D Conversion Start by External Trigger Input

The A/D converter can be started when an external trigger is input. The external trigger is input
from the ADTRG input pin when the trigger enable (TRGE) bit in the A/D control register
(ADCR) is set to 1. When the ADTRG input pin is asserted low, the A/D start (ADST) bit in the
A/D control/status register (ADCSR) is set to 1 and A/D conversion begins. All other operations
are the same as when the ADST bit is set to 1, regardless of whether the mode is single or scan.
For the timing, see figure 14.6.
CK
ADTRG
External
trigger signal
ADST
14.5

Interrupts and DMA Transfer Requests

The A/D converter can generate an A/D interrupt (ADI) request at the end of conversion. The ADI
request is enabled by setting the ADIE bit in ADCSR to 1, or is disabled by clearing the bit to 0.
When ADI is generated, the DMAC can be started. DMA transfers can be performed by
requesting an ADI interrupt by setting the resource select bits (RS3–RS0) in the DMA channel
control register (CHCR) of the direct memory access controller (DMAC). The ADF bit in the A/D
control/status register (ADCSR) is automatically cleared to 0 when the DMAC accesses an A/D
converter register.
Symbol Min
t 10
D
t —
SPL
t 259
CONV
Figure 14.6 External Trigger Input Timing
CKS = 0
Typ Max
— 17
64 —
— 266
A/D conversion
CKS = 1
Min Typ Max
6 — 9
— 32 —
131 — 134
421