250
/
838
Nations Technologies Inc.
Tel
：
+86-755-86309900
：
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
10.3.7
DMA requests
DAC_CTRL.DMAxEN = 1 is configured to enable DMA function. 2 DMA channels correspond to two DACs
respectively.When an external trigger occurs (not a software trigger), a DMA request is generated and the data aligned
with the data hold register is then transferred to the DAC_DATOx register.
When the dual DAC mode is turned on, only one DMA is needed to transmit data, so only one DAC is used to turn
on the DMA function, and two DMA requests will appear when two DACs are turned on.
Note: DMA requests for DAC have no accumulative function, and when the second external trigger occurs before the
response to the first external trigger, the second DMA request cannot be processed and there is no error reporting
mechanism.
10.3.8
The noise
DAC can generate noise, by configuring DAC_CTRL.WxEN[1:0] to "01" to turn on the noise function, by
configuring DAC_CTRL.MAxSEL[3:0] to select which bits of the linear feedback shift register (LFSR) are masked,
the value of LFSR is added to the value of the DAC alignment data holding register and written to the DAC_DATOx
register (overflow bits are discarded). The initial value of LFSR is 0xAAA, and the value of LFSR is updated after 3
APB1 cycles after the trigger event occurs.
Figure 10-5 LFSR algorithm for DAC
X
12
11
10
9
8
7
6
5
4
3
2
1
0
NOR
XOR
X
6
X
4
X
1
X
0
12
