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interfaces:amba [2014/12/23 07:59] – darroninterfaces:amba [2022/07/29 01:23] (current) – [Resources] darron
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-==== ARM Amba ====+==== ARM Amba UART ====
 <wrap right> <wrap right>
 {{:interfaces:amba.jpg?200}} {{:interfaces:amba.jpg?200}}
 </wrap> </wrap>
  
-ARM Amba UARTs are found on ARM systems such as the Raspberry Pi.+These UARTs are found on systems such as the Raspberry Pi.
  
-== Files at ARM == +=== RPi ===
-[[http://infocenter.arm.com/help/topic/com.arm.doc.ddi0183f/DDI0183.pdf|Manual]]+
  
-== Files at RPi == +The following guide is very old now and has mostly become obsolete.
-[[http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf|Peripherals]] +
- +
-==== RPi ====+
  
 By default, the UART is used as the Linux console, this must be disabled to allow general purpose operation. By default, the UART is used as the Linux console, this must be disabled to allow general purpose operation.
 +
 +The following script run as root can solve this.
 <code> <code>
 #!/bin/sh #!/bin/sh
 C=`awk '{ for (i = 1; i <= NF; ++i) { if ($i !~ /ttyAMA0/) { printf $i" " } } printf "\n" }' /boot/cmdline.txt` C=`awk '{ for (i = 1; i <= NF; ++i) { if ($i !~ /ttyAMA0/) { printf $i" " } } printf "\n" }' /boot/cmdline.txt`
 echo $C > /boot/cmdline.txt echo $C > /boot/cmdline.txt
 +sed -i 's/^T0:23:respawn:/#T0:23:respawn:/' /etc/inittab
 </code> </code>
  
-== /boot/config.txt == +High speed modes of operation are also not enabled by default and these should be enabled.
-High speed modes of operation are also not enabled by default and these must be enabled in /boot.+
 <code> <code>
-init_uart_clock=64000000+echo "init_uart_clock=64000000" >> /boot/config.txt
 </code> </code>
 +
 +Reboot the RPi to apply all the settings.
 +
 +===RPi 3===
 +
 +The RPi 3 uses the UART for comms with the the built-in bluetooth module and presents a simple "mini-uart" on the regular pins.
 +
 +To swap the ports around to gain access to the faster port, do the following in config.txt
 +
 +<code>
 +dtoverlay=pi3-miniuart-bt
 +</code>
 +=== Resources ===
 +
 +[[http://infocenter.arm.com/help/topic/com.arm.doc.ddi0183f/DDI0183.pdf|Manual]]
 +
 +[[http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf|Peripherals]]
 +
 +