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Re: [gpsd-dev] Modifying (severly) hardware.html


From: Gary E. Miller
Subject: Re: [gpsd-dev] Modifying (severly) hardware.html
Date: Wed, 15 Apr 2015 13:21:02 -0700

Yo Hal!

On Wed, 15 Apr 2015 13:09:33 -0700
Hal Murray <address@hidden> wrote:

> 
> > 1. Does the serial-to-USB chip pass PPS events handed to the serial
> > side out the USB side as interrrupt packets?  The PL2303 does. FTDI
> > chips do not.
> 
> Are you sure about the FTDI chip not working?  Is that all of the
> FTDI chips or just some/most of them?

USB 1.1 has no concept of 'interrupts", everything is polled.

As for FTDI, I have several USB 2.0 here passing PPS just fine.  I
get under 100 µSec jitter with them.

[    4.158684] usb 5-1: New USB device found, idVendor=0403, idProduct=6001
[    4.161234] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    4.163714] usb 5-1: Product: FT232R USB UART
[    4.166157] usb 5-1: Manufacturer: FTDI
[    4.168574] usb 5-1: SerialNumber: A4YMZFYQ
[    4.175697] ftdi_sio 5-1:1.0: FTDI USB Serial Device converter detected
[    4.177792] usb 5-1: Detected FT232RL
[    4.183157] usb 5-1: FTDI USB Serial Device converter now attached to ttyUSB1

> Is there a simple test case for TIOCMIWAIT?  Can I tell gpsd/gpsmon
> to not use RFC2783?

You need to special build a debug binary.  Maybe rename timepps.h first
to kill the RFC2783.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588



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