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Hi all kindly help me. I'm looking for possible MCU to use, basic requirements would be: 1. on-chip RTC or mcu that can generate accurate time for RTC 2. LCD of around 100 segments, on-chip driver, or software driver 3.SPI,I2C and UART on-chip 4. ARound 32k flash, 1-2k RAM 5. GPIO of aorun 30pins for LCD if software, 1set of SPI,1set of I2C, UART, and 5 extra pins 6. LOW COST
Possible cortex m0,m3 or 8051 family. Help really appreciated
Thank you
What is "accurate time"?
A chip that supports a 32768Hz crystal will produce more accurate time than a chip that makes use of the processor crystal to drive a hw or sw RTC.
The processor crystal isn't produced with as good tolerances. And working at higher frequencies means that it is a smaller and lighter quartz so diffusion of foreign atoms that got stuck inside the casing will result in a larger drift from ageing than with the large and slow 32768Hz crystals.
i did have problem on how to explain that. i found some IC that has dual crystal, one has 32768Hz input, but it didnt say its for RTC. so i was thinking that maybe there some IC of same characteristic so i use term accurate, and that it generate interrupt to create a its RTC. soo my accurate term should be exact as like 2% per month accuracy base on RTC datasheet. upon my search found this: www.holtek.com/.../56R67_668_678.htm
but im more interested on using cortex-m0. also on ST cortexM3, found it on mouser around $3+ which should work + there LCD library, and nxp cortexm0 $.65 but low pin count and I think ill be having problem on generating LCD for my 100segments
so is there some cortex IC or 8051 that fit my requirement?
also, can i log-in on keil forum? as i always enter my email,name....to post?
thank you Per Westermark