From 9b5c8d41521c597c697540f6b942b17763fba394 Mon Sep 17 00:00:00 2001 From: David Schleef Date: Fri, 8 Feb 2002 21:03:58 +0000 Subject: [PATCH] Updated documentation --- comedi/drivers/8255.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/comedi/drivers/8255.c b/comedi/drivers/8255.c index cb30cd18..911bc49b 100644 --- a/comedi/drivers/8255.c +++ b/comedi/drivers/8255.c @@ -26,24 +26,25 @@ Description: generic 8255 support Devices: [standard] 8255 (8255) Author: ds -The classic in digital I/O. Three channels of 8 bit digital I/O, -each channel is I/O configurable, channels 0 and 1 in 8 bit units, -channel 2 in 4 bit units. The driver does not support modes 1 or 2 -yet, since I don't really understand how they would potentially be used. -(Send me email if you want to use these modes.) If and when -modes 1 and 2 are supported, there is a strong possibility that the -3rd channel will be split into two 4-bit channels. (Refer to the -8255 spec for clues as to why.) - -You should configure this driver if you plan to use a board that -has an 8255 chip. For multifunction boards, the main driver will +The classic in digital I/O. The 8255 appears in Comedi as a single +digital I/O subdevice with 24 channels. The channel 0 corresponds +to the 8255's port A, bit 0; channel 23 corresponds to port C, bit +7. Direction configuration is done in blocks, with channels 0-7, +8-15, 16-19, and 20-23 making up the 4 blocks. The only 8255 mode +supported is mode 0. + +You should enable compilation this driver if you plan to use a board +that has an 8255 chip. For multifunction boards, the main driver will configure the 8255 subdevice automatically. This driver also works independently with ISA cards that directly map the 8255 registers to I/O ports, including cards with multiple 8255 chips. To configure the driver for such a card, the option list should be a list of the I/O port bases for each of the 8255 -chips. +chips. For example, + + comedi_config /dev/comedi0 8255 0x200,0x204,0x208,0x20c + */ /* -- 2.26.2