#LOOPBACK SERIAL PORT LINUX HOW TO#
#LOOPBACK SERIAL PORT LINUX DRIVER#

boot/config.txt now has the line enable_uart=1. I have used raspi-config to disable the login shell from being accessible over serial and left the serial port hardware enabled. I'm using a Raspberry Pi Zero with Raspian 4.14 (, Stretch Lite).

#LOOPBACK SERIAL PORT LINUX HOW TO#

I ultimately want to communicate with an Arduino but first I want to understand how to configure the Pi serial UART and its capabilities also I don't have a voltage converter chip like a CD4050 yet. * * A return value of non-zero indicates that it successfully stuffed all * characters from the kernel buffer.I want to connect the TX and RX pins together and from the command line echo some text into /dev/ttyAMA0 and tail the result (from somewhere). * * This function will attempt to stuff of all the characters from the * kernel's transmit buffer into TX BDs. */ #define UCC_WAIT_CLOSING 100 struct ucc_uart_pram /* * Transmit as many characters to the HW as possible. This allows the last few characters to be * sent over the wire. */ #define TX_BUF_SIZE 32 /* * The number of jiffies to wait after receiving a close command before the * device is actually closed. */ #define RX_BUF_SIZE 32 /* The maximum size of the character buffer for a single TX BD. */ #define TX_NUM_FIFO 4 /* The maximum size of the character buffer for a single RX BD. */ #define RX_NUM_FIFO 4 /* The number of buffer descriptors for transmitting characters. */ #define SERIAL_QE_MAJOR 204 #define SERIAL_QE_MINOR 46 /* Since we only have minor numbers 46 - 49, there is a hard limit of 4 ports */ #define UCC_MAX_UART 4 /* The number of buffer descriptors for receiving characters. This decision was made because no Freescale part * has both a CPM and a QE. For the QE * UART, we have major number 204 and minor numbers 46 - 49, which are the * same as for the CPM2. */ static int firmware_loaded /* Enable this macro to configure all serial ports in internal loopback mode */ /* #define LOOPBACK */ /* The major and minor device numbers are defined in *. */ #define UCC_SLOW_GUMR_H_SUART 0x00004000 /* Soft-UART */ /* * soft_uart is 1 if we need to use Soft-UART mode */ static int soft_uart /* * firmware_loaded is 1 if the firmware has been loaded, 0 otherwise. This would normally be defined in qe.h, * but Soft-UART is a hack and we want to keep everything related to it in * this file. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_PPC32 #include /* mfspr, SPRN_SVR */ #endif /* * The GUMR flag for Soft UART. 8323), and YZ is the revision of the SOC, * (e.g. The * filename of the microcode should be fsl_qe_ucode_uart_X_YZ.bin, where 'X' * is the name of the SOC (e.g.

#LOOPBACK SERIAL PORT LINUX DRIVER#

* * If Soft-UART support is needed but not already present, then this driver * will request and upload the 'Soft-UART' microcode upon probe. * * This driver adds support for UART devices via Freescale's QUICC Engine * found on some Freescale SOCs. SPDX-License-Identifier: GPL-2.0 /* * Freescale QUICC Engine UART device driver * * Author: Timur Tabi * * Copyright 2007 Freescale Semiconductor, Inc.

Loopback serial port linux