From: Sean M. <sea...@gm...> - 2010-01-25 19:11:28
|
I've been trying to output some PWM signals using GPTIMER8 through GPTIMER12. However, I've found that GPTIMER2 through GPTIMER12 are not enabled on startup. One suspicious thing I noticed at flash installation is that several patches could not be retrieved from git. Is there a specific image I should be using? Can I enable these timers by writing to a specific register with devmem2? Thanks, Sean |
From: Frank A. <ft...@ya...> - 2010-01-26 18:49:20
|
Sean Matthews wrote: > I've been trying to output some PWM signals using GPTIMER8 through > GPTIMER12. However, I've found that GPTIMER2 through GPTIMER12 are not > enabled on startup. One suspicious thing I noticed at flash > installation is that several patches could not be retrieved from git. > Is there a specific image I should be using? Can I enable these timers > by writing to a specific register with devmem2? > Yes. Here's a script that outputs a PWM signal using GPTIMER8: #!/bin/bash # for omap 35xx, setup pwm associated with general purpose timer 8 for # a frequency of 50hz, 1500us pulse width, then vary pulse width. # On the overo summit board 40 pin # header, the output can be observed on pin 29 (GPIO147_PWM8) devmem2 0x4903e024 w 0x00000000 # set gtp8_TCLR, stop the timer devmem2 0x48002178 w 0x01020102 # set mux for gpt8_pwm_evt devmem2 0x4903e02c w 0xfffc08F0 # set value for gpt8_TLDR, timer load (20ms period) devmem2 0x4903e038 w 0xfffC551c # set value for gpt8_TMAR, timer match (1500us pulse width) devmem2 0x4903e028 w 0xffffffff # set value for gpt8_TCRR, timercounter devmem2 0x4903e024 w 0x00001843 # set gtp8_TCLR, start the timer sleep 3 devmem2 0x4903e038 w 0xfffC36a4 # set value for gpt8_TMAR, timer match 900us) sleep 3 devmem2 0x4903e038 w 0xfffC7394 # set value for gpt8_TMAR, timer match (2100us) sleep 3 devmem2 0x4903e038 w 0xfffC551c # set value for gpt8_TMAR, timer match (1500us) |
From: YatishDravid <yat...@ya...> - 2010-11-26 10:38:34
|
Hi Sean Did you manage to get the PWM working? I am trying to do the same with a overo earth and summit. I am able to get the PWM working at any frequency within the specified range. The problem I am facing is not listed any where here. The problem is how to give accurately X no. of pulses at a set frequency with a 50% Duty cycle. For eg. how can I give 1200 pulses at 30Khz at 50% duty cycle, and stop there? Is there a counter functionality in the PWM where we can set the numbers of pulses it should output? Or alternatively can I set the time duration the PWM is turned on? -Yatish seanWDR wrote: > > I've been trying to output some PWM signals using GPTIMER8 through > GPTIMER12. However, I've found that GPTIMER2 through GPTIMER12 are not > enabled on startup. One suspicious thing I noticed at flash > installation is that several patches could not be retrieved from git. > Is there a specific image I should be using? Can I enable these timers > by writing to a specific register with devmem2? > > Thanks, > Sean > > ------------------------------------------------------------------------------ > The Planet: dedicated and managed hosting, cloud storage, colocation > Stay online with enterprise data centers and the best network in the > business > Choose flexible plans and management services without long-term contracts > Personal 24x7 support from experience hosting pros just a phone call away. > http://p.sf.net/sfu/theplanet-com > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > -- View this message in context: http://old.nabble.com/Enabling-GP-timers-on-Overo-Fire-tp27311900p30308913.html Sent from the Gumstix mailing list archive at Nabble.com. |