Add DHCEN primitive. #261
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Add DHCEN primitive. #261
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Added parts necessary to generate chip databases with DHCEN support for all supported boards. The packing was made with the necessary fuses set. DHCEN is provided as a wire to disable the input MUXes of HCLK, effectively turning off everything that is "beyond" those MUXes. Most of the work happens in the nextpnr part. Signed-off-by: YRabbit <[email protected]>
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For now as a draft for two reasons:
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Added an example of using DHCEN. It uses CLKDIV and CLKDIV2 so it will work on boards that support these primitives. The Tangnano9k board is currently being investigated because there are some unknowns there. Signed-off-by: YRabbit <[email protected]>
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In the example, DHCEN controls all networks at once depending on the state of the button. In the unpressed position, all HCLK networks are disabled (in fact, all used input MUXes are disabled) and only the first LED flashes. When pressed, the second LED begins to show the operation of CLKDIV/CLKDIV2. pr20.mp4tn20.mp4 |
An interesting mechanism for transmitting signals between HCLK banks (or otherwise parties) has been discovered. We have two points, each of which can receive a signal from any HCLK and transmit it to any other HCLK. No complex signals can be transmitted here - the input lines are limited by HCLK_INx, and we also need to see which components can use the output from these two points, but so far the tests are encouraging: it is possible to transmit a signal from the clock pin from one side of the chip to the opposite and feed CLKDIV2 there using just a couple wires! Signed-off-by: YRabbit <[email protected]>
Signed-off-by: YRabbit <[email protected]>
Signed-off-by: YRabbit <[email protected]>
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Seems like this is waiting for YosysHQ/nextpnr#1349 ? |
Optimistic delays for now, pending future revision. Signed-off-by: YRabbit <[email protected]>
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Added parts necessary to generate chip databases with DHCEN support for all supported boards. The packing was made with the necessary fuses set.
DHCEN is provided as a wire to disable the input MUXes of HCLK, effectively turning off everything that is "beyond" those MUXes.
Most of the work happens in the nextpnr part.