> On Apr 28, 2016, at 4:46 AM, frank brewer <frankthebre...@gmail.com> wrote: > > > I just noticed the faster way of toggling pins by using mmap, and after > trying chiragnagpal's example, I could achieve 2.6MHz. > > > > Example was for 1 pin only, now I want to use 8 pins, so I edited .dtc file > as following: > > /* > * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/ > * > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Purpose License Version 2 as > * published by the Free Software Foundation > * > * Original from: > github.com/jadonk/validation-scripts/blob/master/test-capemgr/ > * > * Modified by Derek Molloy for the example on www.derekmolloy.ie > * that maps GPIO pins for the example > */ > > > /dts-v1/; > /plugin/; > > > /{ > compatible = "ti,beaglebone", "ti,beaglebone-black"; > part-number = "DM-GPIO-Test"; > version = "00A0"; > > > fragment@0 { > target = <&am33xx_pinmux>; > > > __overlay__ { > pinctrl_test: DM_GPIO_Test_Pins { > pinctrl-single,pins = < > > > 0x070 0x07 /* P9_11 60 OUTPUT MODE7 - The > LED Output */ > 0x078 0x07 /* P9_12 60 OUTPUT MODE7 - The > LED Output */ > 0x074 0x07 /* P9_13 60 OUTPUT MODE7 - The > LED Output */ > 0x048 0x07 /* P9_14 60 OUTPUT MODE7 - The > LED Output */ > 0x040 0x07 /* P9_15 60 OUTPUT MODE7 - The > LED Output */ > 0x04c 0x07 /* P9_16 60 OUTPUT MODE7 - The > LED Output */ > 0x15c 0x07 /* P9_17 60 OUTPUT MODE7 - The > LED Output */ > 0x158 0x07 /* P9_18 60 OUTPUT MODE7 - The > LED Output */ > > > > > /* OUTPUT GPIO(mode7) 0x07 pulldown, 0x17 > pullup, 0x?f no pullup/down */ > /* INPUT GPIO(mode7) 0x27 pulldown, 0x37 > pullup, 0x?f no pullup/down */ > > > >; > }; > }; > }; > > > fragment@1 { > target = <&ocp>; > __overlay__ { > test_helper: helper { > compatible = "bone-pinmux-helper"; > pinctrl-names = "default"; > pinctrl-0 = <&pinctrl_test>; > status = "okay"; > }; > }; > }; > }; > > > However I could not figure out how to edit the header file used in the > example. Here is the header file of the example: > > #ifndef _BEAGLEBONE_GPIO_H_ > #define _BEAGLEBONE_GPIO_H_ > > > #define GPIO1_START_ADDR 0x4804C000 > #define GPIO1_END_ADDR 0x4804DFFF > #define GPIO1_SIZE (GPIO1_END_ADDR - GPIO1_START_ADDR) > #define GPIO_OE 0x134 > #define GPIO_SETDATAOUT 0x194 > #define GPIO_CLEARDATAOUT 0x190 > > > > > #define PIN (1<<28) > > > > > #endif > > > Questions: > > 1) I could not find START_ADDR, END_ADDR, OE, SETDATAOUT, CLEARDATAOUT from > technical manual. Where can I find them for the pins from P9_11 ... upto P9_18 See AM3358 TRM Table 2-3 GPIO1 > > 2) what is the explanation of the following statement? What does it do? > define PIN ( 1<<28) Take a 1 and left shift by 28. This means bit 28 is set.
>From Section 25.4 134h GPIO_OE 190h GPIO_CLEARDATAOUT 194h GPIO_SETDATAOUT Learn to read the TRM. Section 2.1, Memory Map. Last section of each chapter is the register layout, for example, 25.4 is the GPIO register layout. > > 3) I am going to use it for SPI communication, so since the timing is > critical, and Linux is not RT, there is a possibility that some other > interrupts may damage my communaction. Do you think that it would be a > problem? If yes, what precautions can I get? It is possible because the data is synchronized to the clock. However, I would recommend doing this with PRU. Regards, John > > Regards, > Frank > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/fe2ed36d-96bb-43d3-aeee-9e85fcbfd04b%40googlegroups.com > > <https://groups.google.com/d/msgid/beagleboard/fe2ed36d-96bb-43d3-aeee-9e85fcbfd04b%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/E9FF8757-D1A0-4D9B-9031-E8E0BB2A00CB%40gmail.com. For more options, visit https://groups.google.com/d/optout.
