topic Re: 1788 vs 4357 in LPC Microcontrollers

1788 vs 4357

lpcware — Wed, 15 Jun 2016 18:05:19 GMT

Content originally posted in LPCWare by dhampir on Mon Jul 07 08:00:37 MST 2014
Hi,

since STMs MCUs are limited to a displayclock of 42 Mhz i tried the LPC4357. I was able to run a 7" TFT at 60 MHz. Are there any drawbacks if i switch to the 1788? I don't need the additional processing power but I'm not sure if the lower MCU clock ( 120MHz vs 204 MHz ) will effect the display clock and or memory access.

Thanks for your help
Vincent

Re: 1788 vs 4357

lpcware — Wed, 15 Jun 2016 18:05:19 GMT

Content originally posted in LPCWare by wmues on Mon Jul 07 14:34:20 MST 2014
1788 has only a SDRAM interface with max. 80 MHz Clock. Do a LCD bandwith calculation with the spreadsheet from NXP!

regards
Wolfgang

Re: 1788 vs 4357

lpcware — Wed, 15 Jun 2016 18:05:20 GMT

Content originally posted in LPCWare by mc on Mon Jul 07 14:35:16 MST 2014
Hi Vincent,
Other than processing power the maximum external memory controller(EMC) speed (SDRAM for frame buffer) is important here. I think the best performance with LPC1788 will be: if you run EMC and Cortex M3 core both at 80MHz..LPC4357 has higher EMC speed. You can also consider LPC1857 which has higher EMC speed than LPC1788.

Re: 1788 vs 4357

lpcware — Wed, 15 Jun 2016 18:05:21 GMT

Content originally posted in LPCWare by dhampir on Tue Jul 08 09:09:20 MST 2014
Thank you for the ideas. The 1857 seems to be a good choice although it will not be able to achieve 60MHz displayclock at 24BPP according to the Bandwidth calculator. Achieving 60MHz @24BPP with affordable microcontrollers seems to be near impossible :/. Do I have to get into FPGAs or do you have another idea?

Re: 1788 vs 4357

lpcware — Wed, 15 Jun 2016 18:05:21 GMT

Content originally posted in LPCWare by wmues on Wed Jul 09 14:21:53 MST 2014
SAM9N12/CN11/CN12 from Atmel. Or AT91SAM9G35.