Ludovic- > Thanks for the answer. I guess it's a good point to consider. 300Mhz > is quite attracting, but not the SDRAM... > I guess i got to check how efficient is the cache on this DSP. Here is a document (TI app note SPRA924A) that compares performance of C5502+cache to C5510: http://www.eetasia.com/ARTICLES/2004DEC/A/2004DEC01_MEM_AN.PDF They used SDRAM for the C5502, and only ran it at 200 MHz, to eliminate clock difference with C5510. Results were 1-to-1 in some cases -- fairly impressive. > On the other side, i could keep the 5509A, use the parallel port as > EMIF, and use a cheap double access external RAM to simulate my HPI : > one side connected to my DSP, the other side to my uC. Yep... we went through that same thought process. But the double-access external SRAM (or even single-access, using HOLD/HOLDA) is about the same as using 2x SRAMs for the 32-bit EMIF needed by the C5502. If you want HPI + C55xx, then all roads lead to C5502 :-) Haha, just kidding (only half). -Jeff > -----Message d'origine----- > De : Jeff Brower [mailto:] > Envoyé : mardi 15 février 2005 15:37 > À : Ludovic Tramart > Cc : > Objet : Re: [c55x] 5509A in either HPI or EMIF mode > > Ludovic- > > You may find the answer is: use the C5502. After much study and tradeoff analysis, > that's what we did. > > With C5502, you keep 32-bit EMIF and 8-bit HPI simultaneous. The cache on the C5502 > and 300 MHz clock rate make up at least partially for lack of additional onchip > SRAM. The only real loss was the USB, but with C5509A you need a USB transceiver > anyway, and you can find tiny USB peripheral chips that include both SIE and > transceiver and either give you a UART-type interface or hook up as async EMIF. > > The end result is no loss in board space, and a net decrease in board cost. Plus you > get a UART out of the deal and you still have I2C. > > I guess if A/D converter, MMBus and other C5509A unique peripheral features are > making a big difference, then my analysis is off base. > > -Jeff > > ludovic44fr wrote: > > > > Hi everyone, > > > > We are currently upgrading our product, going from 5410A to 5509A. > > > > I do need to use the EMIF to load my code from flash, and i also need > > to use the HPI to communicate with the Host. > > > > The only problem, is that these 2 ports (EMIF and HPI) are > > multiplexed, on the 5509A, in one port called "Parallel port", and > > that only one can be selected at reset. > > > > TI states in its Peripheral User Guide that it can be reconfigured by > > soft by writing in the EBSR (External Bus Selection Register). OK but... > > > > Unfortunately, in the last revision of the 5509A datasheet, they also > > state : "Dynamic switching of the parallel port, once configured, is > > not recommended." Which means don't do it !!! > > > > Having contacted the EPIC, i got this reply from them : > > > > " You are right, on the C5509A, unlike on the C5409A, you need to make a > > choice at reset between either using the EHPI or the EMIF. > > > > There are 2 ways around using a host interface: > > o either reset the DSP (reset pin) each time you need to make HPI > > access. > > This is very drastic but is the only recommended way in order to the > > HPI to > > responds as per the data sheet operating conditions. > > o implement a protocol to use the EMIF as host interface. > > This means the DSP would have to react to an external event either by: > > o an interrupt, and have an ISR read the host information > > o by pulling a value on an external GPIO > > " > > > > So in definitve, it's seems to me that if you are booting your code > > from flash, you just loose the HPI capability of the DSP !? > > > > As anyone any experience on this DSP and faced the same probem ? > > Or am I reduce to implement my own HPI interface ...? > > > > Thanks for your replies. > > Ludovic |