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CMX608 参数 Datasheet PDF下载

CMX608图片预览
型号: CMX608
PDF下载: 下载PDF文件 查看货源
内容描述: [Integrated Input and Output Channel Filters]
分类和应用:
文件页数/大小: 70 页 / 3411 K
品牌: CMLMICRO [ CML MICROCIRCUITS ]
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RALCWI Vocoder  
CMX608/CMX618/CMX638  
become available until approximately 80ms later. The most convenient sync to use, in this case, is the  
pulse every 20ms.  
At the occurrence of a pulse, the device should be instructed to encode. The next three pulses should be  
ignored. At the next pulse (which is 80ms after the initial encode instruction) the host should read the  
Vocoder packet and transmit it. Every 3rd pulse thereafter, another packet should be read and  
transmitted.  
The slave should supply to its Vocoder a pulse on the sync pin every time it receives a packet of data from  
the master. This will then keep the slave's CODEC in sync with the master's CODEC.  
6.6.  
Setting the Watermarks for the Vocoder Data Input (Output) FIFOs  
Vocoder data is stored in a circular input (output) buffer, configured as a FIFO, before (after) being  
consumed (generated) by the Vocoding process. This buffer is 5 x 20ms long and care must be taken not  
to accidentally overwrite the buffer. For example, if the Vocoder is set to process 4 frames per packet (ie  
an 80ms packet), the low watermark should be set to less than 20ms and the high watermark should be  
set to a non-critical value of 70ms. The low watermark conditions are:  
LowWatermarkValue  
100   
(Frames per Packet 20) Processing Time HostµC VDW ResponseTime 0  
8
Note that the Processing Time and Host µC Response Time are both measured in milliseconds (ms) and  
that a Low Watermark Value of 160, which would be programmed into bits 0 - 10 of the VDWHLWM  
register ($1E), corresponds to a low watermark of 20ms (the same as a single frame of vocoded data).  
6.7.  
Download Protocol for Function Images™  
New features and enhancements to existing functions are available as Function Images. These are  
downloaded into the device over the C-BUS via the DECFRAME register ($10). The data is sent in packets  
of 128 bytes. The Function Imagewill always be a whole multiple of 128 bytes. The following steps  
should be taken to download a Function Image. Please check the documentation supplied with any  
Function Imagewhich may detail a deviation from the following instructions.  
1. Reset the device. This can be achieved by using either the RESETN pin (30), or by writing to the  
C-BUS RESET register ($01).  
2. Wait until the device indicates that it is ready. This can be done by either polling the STATUS  
register ($40) and waiting for bit 15 (RDY) to be set to '1', or waiting until IRQN goes low, and then  
reading the STATUS register to reset it (bit 15 will have been set to '1').  
3. If the process is to be interrupt driven (i.e. using IRQN to indicate a change in the STATUS  
register), then write the value of $C000 to the IRQENAB register ($1F). This will enable interrupts  
for the SVC bit (bit 14), which is used in the download protocol.  
4. Write the value of $01 to the SVCREQ register ($0E). This indicates to the device that a Function  
Imageis to be downloaded.  
5. Wait for bit 14 to be set to '1' in the STATUS register (either by polling or waiting for IRQN to go  
low).  
6. Read the SVCACK register ($2E) and check that bit 0 is set to '1'. This indicates that the device is  
able to accept a Function Image™.  
7. Write 128 bytes of Function Imagedata to the DECFRAME register ($10). This may be done as  
a single 128-byte streaming write, 128 single byte writes or 64 x 2-byte writes.  
2014 CML Microsystems Plc  
59  
D/608_18_38/11  
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