drv2667 - internal waveform memory

Hi, Andreas:

there is a section of "DIRECT PLAYBACK FROM RAM" in data sheet.

You can use this mode for your project.

as each byte is programmable, it can support a large variety of waveforms.

Important notice for this format:

1) this mode data are played at 8kHz data rate

2) Full scale : 0x7f; Middle Scale: 0x00; Negative Scale:0x80

3) total RAM size is 7 pages : page 1 ~ page 7

thanks for your reply, but the answer was not so helpful at the moment.

i know that this driver has a direct playback from 2kb ram, with "8" pages, 8khz datarate, and different modes.

data rate and different modes were already tested with fifo mode.

the problem now is only to know how to use the 2kb ram, because examples do not show how to build its own waveform, the given examples in the datasheet are only in mode 3 and not mode 2

what i need to know is how to use this mode, are the next steps correct?
1. take device out of standby mode 
2. set gain ?
3. end of sequence (no waveform id)

change to page 1
1. set header size (start upper & lower, stop upper & lower, repeat count)
2. write my waveform from start to end into memory ???
    for example simple rectangle with no negative voltage 0x7F, 0x7F, 0x00, 0x00, 0x7F, 0x7F 

change to ctrl. space
1. set go bit

hey thanks, i think i got it.

but a further question, waveforms which can be created now (seen in figures of the datasheet),

will still be available after writing into the memory? so i cannot destroy the sinusoidal waveform?

Hi, Andreas:

the on-chip RAM data except page 0 are randam. So there is no sinusoidal waveform in the RAM until we write into it.

the sinusoidal waves in the data sheet is for demostration purpose, and not actualy embedded/integrated into the on-chip RAM..

Hi,Thank you very much,,i will look in to it and get back for future clarifications.Thank u very much sir

Hi Mr.Peter,

i have tried to use the RAM manager..unfortunatly i dont understand how to generate Amplitude modulated waveform of 2500Khz carrier + 50Hz modulating sine wave. i can see that software can generate sine waves of frequqncy with ramps..mostly looks like mode 3 functions,i was unable to generate AM signal or some custom pattern..please help me generate it.Thank u

Hi,

is any one Else who knows how to generate an AM wave with 2500khz+50hz sine
using RAM mode of drv2667

Thanks

Hi,

i found some way to manually generate the wavetable to generate the AM.but could please give me some code references which can help me figure out proper direct play procedure..and also is it possible to increase the sampling rate from 8Khz to higher rate..if it is fixed is there any similar part with higher sampling rate?please help me we are running out of time

Thank u

Hi,

the sample rate is fixed at 8KHz.

for direct play, how many bytes is the wavetable?

if we can save it into the DRV2667 internal memory, the play procedure is very simple.

here is the play procedure for waveforms inside internal memory:

 register write (0x02, 0x00) //out of standby

 register write(0x03, xxx) // waveform index

 register write(0x04, 0x00) //end of sequencer

 register write(0x02, 0x01) //play

if the wavetable is bigger and we cannot save it into DRV2667 internal memory, we need to use FIFO playback mode.

play procedure for FIFO playback:

 register write (0x02, 0x00) //out of standby

while( loop )

  register write (0x0b, data[x])

Hi thank you

at present,the wave table is 20ms around 160bytes,.may be we may increase it to 100ms -around 800bytes. we may use repeat cycles. please provide us some code snippets to store data,and play the same again and again ..totally we may need to continously play for 30 min.so there will so many loopings using some externel timer ..