- #Cannot find tri state buffer in logicworks how to#
- #Cannot find tri state buffer in logicworks 32 bit#
I hope i can use the following workaround: I would just wait initially until the Thread_3_DMA_Ready (Thread 3 is USB->GPIF) flag goes high (deasserted) for the first time, before reading or writing using just the watermark flags. It mentions problems using only the watermark flags in the way i described above. My final question regards (potential) bugs with the watermark flags: I found the attached memo in this post: . Is that sensible? I'm afraid of +-1 erros on the watermark level, but 255 seems like a sensible value. When i'm finished with the burst, the flag should should show if i can start another burst, regardles of all the delays. Shortly after starting the burst, the flag should change or not. If i see a high level on the flag (deasserted) i can read/write a burst of 256 words. Since data should always be written and read in bursts of 1 kB, i hope i can just use watermark flags with a watermark level of 255. That introduces a lot of additional delay on the flags, so i hope i can the following scheme: To fix this i plan to treat the flags as asychronous signals and use snychronizers in the FPGA to make sure things are stable. The next question is regarding partial flags: With a 100 MHz Clock, i can't meet the setup and hold times on the flag signals. I plan to configure all flags with active low polarity and initial value low, and then wait with reading/writing until i see a high level on the line. Is that correct? This seems very unintuitive for a "ready" flag.
My first question is on the polarity of the "Thread_X_DMA_Ready" and "Thread_X_DMA_Watermark" flags: It seems that you have to wait until the the flag is deasserted before reading/writing. I hope i can use the firmware provided with AN65974 with very little modifications.
#Cannot find tri state buffer in logicworks 32 bit#
I plan to use a synchronous 32 Bit Interface to the FX3 with a 100 MHz clock. With a decoder only four control lines are needed.I have a couple of question regarding the FX3 GPIF Interface. A circuit needing to select among sixteen devices could have sixteen control lines to select which device should “listen”. Usually it is easier to design ladder logic from boolean equations or truth tables rather than design logic gates and then “translate” that into ladder logic.Ī typical application of a line decoder circuit is to select among multiple devices.
#Cannot find tri state buffer in logicworks how to#
For an eight-bit adder we only know how to sum eight bits by summing one bit at a time. If you do it might look something like this:įor some logic it may be required to build up logic like this. You might also consider making a 2-to-4 decoder ladder from 1-to-2 decoder ladders. In a similar fashion a 3-to-8 line decoder can be made from a 1-to-2 line decoder and a 2-to-4 line decoder, and a 4-to-16 line decoder can be made from two 2-to-4 line decoders. Replacing the 1-to-2 Decoders with their circuits will show that both circuits are equivalent.
An alternate circuit for the 2-to-4 line decoder is: Larger line decoders can be designed in a similar fashion, but just like with the binary adder there is a way to make larger decoders by combining smaller decoders. Developed into a circuit it looks like the Figures below.
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