TMP92CF30
2009-06-12
92CF30-77
(6)
HDMAE (DMA Operation Enable Register)
The HDMAE register is used to enable or disable the DMAC operation.
Bits 0 to 5 correspond to channels 0 to 5. Unused channels should be set to “0”.
HDMAE Register
7
6
5
4
3
2
1
0
bit Symbol
DMAE5
DMAE4
DMAE3
DMAE2
DMAE1
DMAE0
Read/Write
R/W
Reset State
0
0
0
0
0
0
HDMAE
(097EH)
Function
DMA channel operation
0: Disable
1: Enable
Note: Read-modify-write instructions can be used on this register.
Figure3.6.7 HDMAE Register
(7)
HDMATR (DMA Maximum Bus Occupancy Time Setting Register)
The HDMATR register is used to set the maximum duration of time the DMAC can
occupy the bus. The TMP92CF30 does not have priority levels for bus arbitration.
Therefore, once the DMAC owns the bus, other masters must wait until the DMAC
completes its transfer operation and releases the bus. This could lead to problems in
the system. To avoid such a situation, the DMAC limits the duration of its bus
occupancy by using this timer register. When the DMAC occupies the bus for the
duration of time set in this register, it releases the bus even if the specified DMA
operation has not been completed yet. After waiting for 16 states, the DMAC asserts a
bus request again to execute the rest of the DMA operation.
The DMAC counts the bus occupancy time regardless of which channel is occupying
the bus. To set the maximum bus occupancy time, ensure that the HDMAE register is
set to “00H” and set HDMATR<DMATE> to “1” and <DMATR6:0> to the desired value.
Note: In case of using S/W start with HDMA, transmission start is to set to “1” DMAR register. However DMAR
register can't be used to confirm flag of transmission end. DMAR register reset to “0” when HDMA release bus
occupation once with HDMATR function.
HDMATR Register
7
6
5
4
3
2
1
0
bit Symbol
DMATE
DMATR6 DMATR5
DMATR4
DMATR3
DMATR2
DMATR1 DMATR0
Read/Write R/W
Reset State
0
0
0
0
0
0
0
0
HDMATR
(097FH)
Function Timer
operation
0: Disable
1: Enable
Maximum bus occupancy time setting
The value to be set in <DMATR6:0> should be obtained by
“maximum bus occupancy time / (256/f
SYS
)”.
“00H” cannot be set.
Note: Read-modify-write instructions can be used on this register.
Figure3.6.8 HDMATR Register
Summary of Contents for TLCS-900/H1 Series
Page 652: ...TMP92CF30 2009 06 12 92CF30 650 ...