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Does anyone know of any example code to get the VC33 to talk to the AD50C, as they're set up on the Spectrum Digital ezDSP? I think I'm most of the way there, but somethings amiss... Bill |
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VC33 to AD50C code
Started by ●January 27, 2004
Reply by ●January 27, 20042004-01-27
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Hi Bill I am no expert on the TLC320AD50 (sorry no code), but in some ways it is quite similar to the TLC32040 codec (C31 DSK), but in other ways very different. What I see is a similar interface that has been augmented with the ability to block accidental reprogrammation via an inadvertant DAC value. The sticky point is probably codec 'secondary' programmations, or that you have got stuck in a mode and cant get out. How are 2nd XMIT's blocked or forced (how I interpret the DS) ------------------------- In the 15b DAC mode the data words LSB bit is used to signal that a secondary transmit is being requested. On the other hand, if modeb, using the LSB would not be feasible since that bit is now effectively random. Therefor in 16b mode a method of forcing 15b DAC mode or forcing secondary transmits (FC pin) is needed. If modeb ----------- Program like a TLC32040, but be sure to write the 15/16b mode bit *LAST* as this will block subsequent programmation attempts using LSB initiated transfers. If modeb ----------- LSB initiated secondaries are blocked in 16b mode and therefor require FC=1. The timing is important since the rising edged of FSX latches the signal. Just be sure that nothing else is going on that could delay the ISR. Also, serial port data is clocked out from a *copy* of the DXR register delaying the data stream. In the 15b mode the LSB is nominally used to initiate programmation and this works since the stream is continuous. However, in 16b mode the data stream must lead the FC=1 condition. Hit Reset and Reprogram ----------------------- Another option would be to simply pull the reset and reprogram the codec. This might produce a pop, but it would get you back into a mode that can be programmed. As a recap, I see two potential snares 1) When the DAC is put into 16b mode, LSB initiated programmation is blocked 2) Using FC requires knowing that the serial port has a built-in delay Hope this helps, Keith Larson ---------------- At 07:51 AM 1/27/04 -0500, you wrote: Does anyone know of any example code to get the VC33 to talk to the AD50C, as they're set up on the Spectrum Digital ezDSP? I think I'm most of the way there, but somethings amiss... Bill +--------------------------+ | Keith Larson | | Member Group Technical Staff | | Texas Instruments Incorporated | | | | 281-274-3288 | | | | www.micro.ti.com/~klarson (TI internal web only) | |--------------------------+ | TMS320C3x/C4x/VC33 Applications | | | | TMS320VC33 | | The lowest cost and lowest power 500 w/Mflop | | floating point DSP on the planet! | | | | Web: focus.ti.com/docs/toolsw/folders/print/tmdsdsk33.html | | Code: www-s.ti.com/sc/psheets/sprc147/sprc147.zip | +--------------------------+ |
