LPC1769 System tick timer question

[lpcware]

Content originally posted in LPCWare by yannis on Tue Oct 16 09:53:02 MST 2012
I am using gyroscope sensor with my LPC1769 now. To calculate the related angles, I need the "time"!!
I am trying to implement this with System tick timer, but what I'm not familiar is how to related the value get from this timer to a real time value??

[lpcware]

Content originally posted in LPCWare by frame on Mon Oct 22 05:49:17 MST 2012
Seems to me this thread is about to go astray...

Why using the RTC for pacing a sensor read ?
This requires more of a short term accuracy in the millisecond range. The SysTick timer or some general purpose timer should serve you well.

[lpcware]

Content originally posted in LPCWare by ex-kayoda on Mon Oct 22 03:50:25 MST 2012
Unfortunately this 400kHz FRAMs (testing http://be.farnell.com/fujitsu/mb85rc128pnf-g-jne1/ic-memory-fram-128k-i2c-8sop/dp/1831995 since 2010) are not really faster than a modern 1MHz EEPROM in my boards, which are writing a few bytes, but reading a few thousand bytes :eek:

[lpcware]

Content originally posted in LPCWare by serge on Mon Oct 22 03:15:34 MST 2012
Indeed i don't think that RTC chips come already with fram memory and i agree those fram memory chips are expensive especialy a 128K x 8 (Digikey FM24V10-GTR = 9.18 euro + VAT)
Actualy I don't need that much memory to store some parameters so i can do with the smaller fram memorys which are around €2 a piece.:p Still expensive for mass production but i only make small series. http://be.farnell.com/fujitsu/mb85rc16pnf-g-jne1/fram-16k-i2c-3v-8sop/dp/2070257

[lpcware]

Content originally posted in LPCWare by ex-kayoda on Mon Oct 22 01:15:51 MST 2012

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Quote: Serge
EEPROM??:eek:

I don't use eeprom anymore since i discovered FRAM. No waitstates during write and (almost) same specs. Fram is as good as nvram.:D

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#1 Perhaps you can help me out and tell me which RTC is including FRAM today :confused:

#2 Unfortunately 128k * 8bit FRAM  is a little bit expensive. I get the impression that chips are cheaper in Belgium :confused:

[lpcware]

Content originally posted in LPCWare by serge on Mon Oct 22 01:00:42 MST 2012
EEPROM??:eek:

I don't use eeprom anymore since i discovered FRAM. No waitstates during write and (almost) same specs. Fram is as good as nvram.:D

And indeed the DS3231 is expensive.

I should migrate to Microchip RTC too.:p

[lpcware]

Content originally posted in LPCWare by ex-kayoda on Mon Oct 22 00:52:28 MST 2012

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Quote: Serge
example: [B]Maxim-IC DS3231 [/B]

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:confused:

SOIC16 without NVRAM and EEPROM :eek:

And it's price :mad:

Migrated to Microchip RTC like MCP79410 long time ago :)

[lpcware]

Content originally posted in LPCWare by serge on Mon Oct 22 00:02:12 MST 2012
@ Kayoda

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Quote:
:confused: What's wrong with RTC of LPC1769 :eek:

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it's accuracy?
When i need an accurate RTC then i add an external RTC to my design for example: [B]Maxim-IC DS3231 [/B]

Also see the LPC1769 errata sheet under 3.11:

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Quote:
[FONT=Arial][SIZE=2][COLOR=#007088][FONT=Arial][SIZE=2][COLOR=#007088][FONT=Arial][SIZE=2][COLOR=#007088]
[LEFT][B]Problem:[/B][/LEFT]
[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Arial][SIZE=2][FONT=Arial][SIZE=2][LEFT][B]The RTC does not work reliably within the temperature specification.[/B][/LEFT]
[/SIZE][/FONT][/SIZE][/FONT][FONT=Arial][SIZE=2][COLOR=#007088][FONT=Arial][SIZE=2][COLOR=#007088][FONT=Arial][SIZE=2][COLOR=#007088][LEFT][B]Work-around:[/B][/LEFT]
[/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][/COLOR][/SIZE][/FONT][FONT=Arial][SIZE=2][FONT=Arial][SIZE=2][B]None.[/B]

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:eek:
[/SIZE][/FONT][/SIZE][/FONT]

[lpcware]

Content originally posted in LPCWare by yannis on Wed Oct 17 09:49:26 MST 2012
I think we solve the problem now!! Actually it matters really a lot when there is "printf" inside the function. That's why our time also get wrong!!

[lpcware]

Content originally posted in LPCWare by ex-kayoda on Wed Oct 17 01:59:22 MST 2012

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Quote: yannis
I am using gyroscope sensor with my LPC1769 now. To calculate the related angles, I need the "time"!!

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:confused:   What's wrong with RTC of LPC1769 :eek: