On Thu, 16 Feb 2017 08:34:30 +0100 Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > Hi Antony, > > On Wed, Feb 15, 2017 at 10:12:25AM +0300, Antony Pavlov wrote: > > This patch series makes it possible to use FT2232H ACBUS[7:0] > > pins as gpio pins from sandbox barebox. > > > > I have tested output gpio functionality by connecting > > a LED to ACBUS[0] and lightening it with gpio_direction_output > > and gpio_set_value barebox commands. > > > > Also I have performed input test with ACBUS[0] -> ACBUS[1] loopback. > > > > The main goal of adding gpio functionality to sandbox barebox > > is using it for connecting real i2c and spi devices to sandbox barebox > > (not tested yet). > > I just read that the FT2232H can even do native I2C and SPI, so no gpio > bitbanging would be necessary. I suppose that gpio support itself is valuable. > Would it be possible to use this mode instead? Yes, FT2232H has MPSSE acellerator. Using MPSSE one can increase FT2232 I2C/SPI performance dramatically. I have compared two FT2232 I2C realizations (bitbang and libmpsse, see https://github.com/frantony/mprog/tree/master/i2c_access). on reading of 8 KiB data block from I2C eeprom. libmpsse's bandwidth is 6 KiB per second, bitbang's bandwidth is only 73 bytes per second (nearly 100 times worse). Alas, I have no time to realize ftdi fast i2c/spi support for barebox in the nearest future > Otherwise I think there should be a possibility to specify which, if > any, FT2232H chip barebox uses. I'll add cmdline options to select FT2232H chips on USB bus in v2 patchseries. Also I'll check i2c bitbang support. I can connect ds1307 rtc or at24 eeprom). -- Best regards, Antony Pavlov _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
