**** BEGIN LOGGING AT Thu Jul 06 03:00:03 2017 Jul 06 14:27:35 Is it possible to generate a pulse in ms resolution with BBB (let say pulse of 2ms but not more then 2ms) ? or linux is not realtime enough to work at promise such resulotion Jul 06 14:32:39 cyberguy_: depends, but especially on a BBB one would usually use the PRU Jul 06 14:47:13 LetoThe2nd : what about timers and interrupts? can i configure an interrupt to run each 2ms? Jul 06 14:47:41 cyberguy_: this is not how linux works Jul 06 14:48:57 technically you could write a driver that claims a timer and a gpio and then does stuff. but if you want to do things like that, you probably actually do not want linux, but some RTOS Jul 06 14:49:43 well, i actually need linux for almost all my tasks, i just need to generate a pulse with 2ms with periodically at some pin Jul 06 14:50:11 then look at the pru. its exactly what they are meant for. Jul 06 14:51:00 great, thanks Jul 06 14:51:27 another question , DRAM has a register to configure the impedance of the traces. Jul 06 14:51:38 do you know where can i see the DRAM driver to check which value is configured there? Jul 06 15:23:05 I got a beaglebone blue when they were first released but haven't touched it yet. Should I flash it with the latest image (2017-3-19) to make sure I've got the latest version of the helper scripts for the motors and sensors? Jul 06 15:40:21 cyberguy_: why not configure a PWM output? Jul 06 15:40:34 for generating the periodic pulse Jul 06 15:40:37 zmatt: great idea. just wanted to ask about it Jul 06 15:40:54 the pwm is at ms resolution Jul 06 15:40:58 no Jul 06 15:41:01 not in hw anyway Jul 06 15:41:13 what is the resolution then? Jul 06 15:41:14 more like 10ns resolution Jul 06 15:41:21 wow. amazing excellent Jul 06 15:41:29 i'll google about it, i can also do it from cmd line right? Jul 06 15:43:49 as with most peripherals you can use cape-universal, or an overlay, or a customized dtb Jul 06 15:44:54 there are also three types of peripherals to choose from that can generate pwm: the eHRPWM peripherals, the eCAP peripherals, and Timers 4-7 Jul 06 15:46:30 ms resolution is also very coarse, so there are more options like using the gpio led driver with the "oneshot" trigger Jul 06 15:46:50 zmatt : what if i need a fast logic from 2 input signals, for instance generate AND on output pin from two inputs, and the performance need to be fast, how would you recommand implementing it? Jul 06 15:47:12 pru Jul 06 15:47:19 okay. Jul 06 15:47:26 actually, I'd recommend using an AND gate in hw :P Jul 06 15:50:28 hehe... yeah , but that was just example, we want to keep our board as flexible as possible. Jul 06 15:51:14 for fast customizable combinatorial logic even pru seems misplaced, a cpld or small fpga might be more appropriate Jul 06 15:51:39 impossible to say from your vague problem description Jul 06 15:53:32 drive strength and and termination impedance for the ram's drivers is configured in the sdram config register in EMIF. the values for the memory controller's drivers are in the control module Jul 06 15:56:05 see TRM section 7.3.5.3 for the first Jul 06 15:56:53 (just to be sure: i'm using rev O of the TRM) Jul 06 15:57:26 sections 9.3.1.87 - 9.3.1.91 for config of memory controller's drivers Jul 06 15:57:41 hmm, where was ODT config for the memory controller... Jul 06 15:58:06 oh wait that might actually be in EMIF again, not in control module Jul 06 15:59:26 bingo, section 7.3.5.33 Jul 06 16:01:24 zmatt: can I configure PWM for a single pulse? Jul 06 16:02:06 the hw is capable of that, dunno if the linux drivers are Jul 06 16:03:22 I generally just bypass the drivers and use the peripherals directly from userspace Jul 06 16:03:55 (by declaring the peripherals as uio devices) Jul 06 16:07:57 zmatt: another question (if poissible... you're my guru...) , the DRAM has a register to configure the traces impedance. where is the driver for the DRAM ? i want to check the default value written there.... Jul 06 16:08:44 ehm, look at your screen? I literally just told you that Jul 06 16:15:21 sorry for my lame question, what is TRM ? what is all these sections? it's the linux package documentation? Jul 06 16:15:56 seriously.. Jul 06 16:16:43 AM335x Technical Reference Manual, go fetch it -> http://www.ti.com/product/AM3358/technicaldocuments#doctype6 Jul 06 16:16:58 oh hey, rev P is out, lemme recheck the section numbers then Jul 06 16:18:08 so that is from AM335x TRM, but i'm talking about the SW . how can i verify which value is configured there by the kernel/driver/u-boot/SPL/else.... Jul 06 16:18:34 by reading the appropriate registers, documented in the TRM Jul 06 16:19:01 (or fishing them out of the u-boot source code) Jul 06 16:19:02 hardware runs software, film at 11 Jul 06 16:19:45 ok, section numbers are still the same Jul 06 16:20:13 okay thanks, so i need to verify with u-boot source code if it changes these values? Jul 06 16:21:21 you don't have to check *if* it configures these values, I can tell you it does since otherwise you don't have any external ram working, which would be a bit problematic for running linux :P Jul 06 16:21:52 so oi need to check what values is written to the impedance register ? Jul 06 16:21:59 at u-boot source Jul 06 16:22:02 ? Jul 06 16:22:33 why you are asking questions which already got answered? Jul 06 16:22:43 I told you exactly which registers contain relevant settings Jul 06 16:23:10 I told you you can either read those registers directly, or check what values are configured into those registers by examining the u-boot source code Jul 06 16:23:15 reading them directly is probably easier Jul 06 16:23:48 and now I think you've run out of credits for asking noob questions for today Jul 06 16:25:09 (ok maybe they're not noob questions, except they are if you're doing bringup of custom hw) Jul 06 23:24:38 feisty Jul 07 01:17:21 I am kumar from India. I am testing BBB with software called CoDeSys. I need to have one more ethernet port. How to add ? Jul 07 01:25:09 kumar: the am335x itself supports two ethernet ports, but the second one cannot be used on the BBB (some of those pins are used for other purposes) Jul 07 01:26:37 so, options are: 1. use a different board that has two eth ports 2. use an usb-ethernet adapter 3. use vlans and a managed switch to split vlans into separate ports Jul 07 01:45:45 About your point 3... vlans means virtual LAN? Jul 07 02:00:28 yes Jul 07 02:33:17 has anyone here tried to use openocd to do jtag debugging with the am335x Jul 07 02:33:42 (yes, i've already soldered the header to the jtag pads on the back of the board and also have that god damn eighty dollar cable for interfacing with it) **** ENDING LOGGING AT Fri Jul 07 03:00:02 2017