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MAX32660 User Guide
Maxim Integrated
Page 76 of 195
When running in normal mode without buffer chaining (
.rlden =
.chdien
bit only. An
interrupt is generated upon DMA completion or an error condition (bus error or time-out error).
When running in buffer chaining mode (
.rlden =
.chdien
and
.ctzien
bits.
The CTZ interrupts occur on completion of each DMA (count reaches zero and reload occurs). The setting of
.chdien
ensures that an error condition generates an interrupt. If
.ctzien =
0, then the only interrupt
occurs when the DMA completes and
.rlden =
0 (final DMA).
7.9
Channel Time-outs
Each channel can optionally generate an interrupt when its associated request line is inactive for a given period of time. An
example use of this feature is to determine an idle UART receive channel. Each channel has a dedicated 10-bit timer
allowing use of a different timeout value.
7.10
10-bit Timer
Use the settings in the
r gist r t c ntr l ach chann l’s 10
-bit timer. Scale the input clock for the timer using
the
.pssel
field. The options available are:
•
f
HCLK
256
•
f
HCLK
64K
•
f
HCLK
16M
Note: HCLK is the AHB interface clock that enables the memory system to run at a different frequency than the system clock,
the cache controller, and the event monitor.
.tosel
field sets the time the 10-bit timer counts until generating an interrupt.
The 10-bit timer resets whenever any of the following conditions occur:
•
The DMA request line programmed for the channel is activated.
•
The channel is disabled for any reason (
.ch_st =
0).
To disable the 10-bit timer, set the
.pssel
field to 0.
Normally, the 10-bit timer starts when the channel is enabled and the
.pssel
field is non-zero. However, if
.reqwait =
1, then the timer starts counting only after the first DMA request is received from the peripheral.
To calculate the time-out period, use
Equation 7-1: Timeout Equation for Standard DMA
𝑇
𝑡𝑖𝑚𝑒𝑜𝑢𝑡
= 𝑇
𝐻𝐶𝐿𝐾
× 𝑁
𝑝𝑠𝑠𝑒𝑙
× 𝑁
𝑡𝑜𝑠𝑒𝑙
For example, if
T
HCLK
=
1
90MHz
,
N
pssel
= 0x2 (65,536 timer prescaler)
, and
N
tosel
= 0x3 (32 clocks)
, then the time-out
calculation is:
T
timeout
= (
1
90,000,000
) × 65,536 × 32 = 23.3ms
Содержание MAX32660
Страница 4: ...MAX32660 User Guide Maxim Integrated Page 4 of 195 8 UART 84 9 Real Time Clock RTC 96 10 Timers 105...
Страница 7: ...MAX32660 User Guide Maxim Integrated Page 7 of 195 15 Trademarks 195 16 Revision History 195...
Страница 14: ...MAX32660 User Guide Maxim Integrated Page 14 of 195 Figure 2 1 MAX32660 High Level Block Diagram...