Fixed the requirement for -lm

[wiringPi.git] / gpio / gpio.1

diff --git a/gpio/gpio.1 b/gpio/gpio.1
index 2d3b86084eaed60ad0970e7f9ec00b903b5ecf42..673ebbe2c8db2c2d215fee702db2fd4ec223825f 100644 (file)
--- a/gpio/gpio.1
+++ b/gpio/gpio.1
@@ -1,4 +1,4 @@
-.TH "GPIO" "January 2015" "Command-Line access to Raspberry Pi's GPIO"
+.TH GPIO 1 "September 2015" wiringPi "Command-Line access to Raspberry Pi's GPIO"
 
 .SH NAME
 gpio \- Command-line access to Raspberry Pi's GPIO
@@ -185,9 +185,11 @@ Print a list (if any) of all the exported GPIO pins and their current values.
 .TP
 .B export
 Export a GPIO pin in the \fI/sys/class/gpio\fR directory. Use like the
-mode command above however only \fIin\fR and \fIout\fR are supported at
-this time. Note that the pin number is the \fBBCM_GPIO\fR number and
-not the wiringPi number.
+mode command above however only \fIin\fR, \fIout\fR, \fIhigh\fR and
+\fRlow\fR are supported at this time. Note that the pin number is the
+\fBBCM_GPIO\fR number and not the wiringPi number. The \fIhigh\fR and
+\fIlow\fR commands pre-set the output value at the same time as the
+export to output mode.
 
 Once a GPIO pin has been exported, the \fBgpio\fR program changes the
 ownership of the \fI/sys/class/gpio/gpioX/value\fR and if present in
@@ -249,12 +251,9 @@ on the associated /dev/ entries so that the current user has access to
 them. Optionally it will set the I2C baudrate to that supplied in Kb/sec
 (or as close as the Pi can manage) The default speed is 100Kb/sec.
 
-Note that on a Pi with a recent 3.18 kernel with the device-tree structure
-enable, the load may fail until you add:
-
-.I dtparam=i2c=on
-
-into \fB/boot/config.txt\fR to allow user use of the I2C bus.
+Note: On recent kernels with the device tree enabled you should use the
+raspi-config program to load/unload the I2C device at boot time.
+(or disable the device tree to continue to use this method)
 
 .TP
 .B load spi
@@ -267,12 +266,9 @@ this has fixed the buffer size. The way to change it now is to edit
 the /boot/cmdline.txt file and add on spdev.bufsiz=8192 to set it to
 e.g. 8192 bytes then reboot.
 
-Note that on a Pi with a recent 3.18 kernel with the device-tree structure
-enable, the load may fail until you add:
-
-.I dtparam=spi=on
-
-into \fB/boot/config.txt\fR to allow user use of the I2C bus.
+Note: On recent kernels with the device tree enabled you should use the
+raspi-config program to load/unload the SPI device at boot time.
+(or disable the device tree to continue to use this method)
 
 .TP
 .B gbr