The FireStarter: a WiP CPC to RP2350B (Pico) Board derailed thread

[McArti0]

20MHz at QPI is too SLOW... for CPC RAM of course...

Nice?

[pelrun]

@McArti0 Nobody comes into this world knowing how to do everything perfectly. I personally know the pitfalls because I've already fallen into them, not because I'm brilliant. Discouraging people who are enthusiastic but still inexperienced is weak sauce.

And it's not like it's obvious what the problems are from just looking at the big numbers. It's the tiny details that bite, like setup and hold times, interrupt latency, gpio bank organisation, etc etc etc. Most of the time raw cpu clock speed is irrelevant, because doing things manually is always too slow. It comes down to creative manipulation of hardware peripherals to get enough throughput, and most microcontrollers have very fixed ideas about what their peripherals can do. Some of the issues that look impossible are trivially avoided, and some of the issues that look trivial are absolute dealbreakers.

[Brocky]

20MHz at QPI is too SLOW... for CPC RAM of course...

Nice?

help me to understand why would be nice
im guessing it coz its quad pumped? so effectively 5mhz or slower?? ...

im not perfect and i will need help... isnt that what the community is for?...i will get things wrong, but im happy to be corrected..but i also realize noone is perfect!....

...i will eventually start my own thread when i work out a easy solution that everyone can build from modules... 

[McArti0]

help me to understand
 i will need help...

https://www.google.com/search?q=ram+qpi+20MHz

Google answer...

https://www.issi.com/US/product-serial-sram-and-serial-ram.shtml

Serial SRAM and Serial RAM
Industry Standard SPI and QPI

The largest RAM 20MHz is ...IS62-65WVS5128F

Manual...

https://www.issi.com/WW/pdf/IS62-65WVS5128FALL-BLL.pdf

Byte Read Operation in SQI Mode

"Whaaaaatt?" 12 clocks for one read??? 

1/20MHz = 50ns,    50*12= 600ns

Ohh how slow... Not be nice  .

@Gryzor please cut off to new topic help for Brocky. This is not good place for this.

[Brocky]

help me to understand
 i will need help...

https://www.google.com/search?q=ram+qpi+20MHz

Google answer...

https://www.issi.com/US/product-serial-sram-and-serial-ram.shtml

Serial SRAM and Serial RAM
Industry Standard SPI and QPI

The largest RAM 20MHz is ...IS62-65WVS5128F

Manual...

https://www.issi.com/WW/pdf/IS62-65WVS5128FALL-BLL.pdf

Byte Read Operation in SQI Mode

"Whaaaaatt?" 12 clocks for one read??? 

1/20MHz = 50ns,    50*12= 600ns

Ohh how slow... Not be nice  .

@Gryzor please cut off to new topic help for Brocky. This is not good place for this.

no need for that gryzor... this is all i needed to know...

@McArti0 you have my idea all wrong... im talking about the comms between 2 micros... the ram will be in a buffer on the 2nd mcus ram.. SPI can be sped up with the correct mcus upto  around 100mhz iirc...(1st mcu is connection to cpcs bus + connection to 2nd mcu)
if extra ram would be needed then PSRAM can be used on esp32 with good speed 80mhz - ~20mb/s