343 lines
12 KiB
C
343 lines
12 KiB
C
// #################################################################################################
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// # << NEORV32 - TWI Bus Explorer Demo Program >> #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License #
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// # #
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// # Copyright (c) 2023, Stephan Nolting. All rights reserved. #
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// # #
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// # Redistribution and use in source and binary forms, with or without modification, are #
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// # permitted provided that the following conditions are met: #
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// # #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of #
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// # conditions and the following disclaimer. #
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// # #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
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// # conditions and the following disclaimer in the documentation and/or other materials #
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// # provided with the distribution. #
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// # #
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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
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// # endorse or promote products derived from this software without specific prior written #
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// # permission. #
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// # #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
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// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
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// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
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// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
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// # OF THE POSSIBILITY OF SUCH DAMAGE. #
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// # ********************************************************************************************* #
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// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
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// #################################################################################################
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/**********************************************************************//**
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* @file demo_twi/main.c
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* @author Stephan Nolting
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* @brief TWI bus explorer.
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**************************************************************************/
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#include <neorv32.h>
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#include <string.h>
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/**********************************************************************//**
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* @name User configuration
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**************************************************************************/
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/**@{*/
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/** UART BAUD rate */
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#define BAUD_RATE 19200
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/**@}*/
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// Prototypes
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void scan_twi(void);
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void set_clock(void);
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void send_twi(void);
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void check_claimed(void);
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void toggle_mack(void);
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uint32_t hexstr_to_uint(char *buffer, uint8_t length);
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void print_hex_byte(uint8_t data);
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// Global variables
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int bus_claimed;
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/**********************************************************************//**
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* This program provides an interactive console to communicate with TWI devices.
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*
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* @note This program requires the UART to be synthesized.
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*
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* @return 0 if execution was successful
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**************************************************************************/
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int main() {
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char buffer[8];
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int length = 0;
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bus_claimed = 0;
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// check if UART unit is implemented at all
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if (neorv32_uart0_available() == 0) {
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return 1;
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}
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// capture all exceptions and give debug info via UART
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// this is not required, but keeps us safe
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neorv32_rte_setup();
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// setup UART at default baud rate, no interrupts
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neorv32_uart0_setup(BAUD_RATE, 0);
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// intro
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neorv32_uart0_printf("\n--- TWI Bus Explorer ---\n\n");
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// check if TWI unit is implemented at all
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if (neorv32_twi_available() == 0) {
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neorv32_uart0_printf("No TWI unit implemented.");
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return 1;
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}
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// info
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neorv32_uart0_printf("This program allows to create TWI transfers by hand.\n"
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"Type 'help' to see the help menu.\n\n");
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// configure TWI, second slowest clock, no clock stretching
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neorv32_twi_setup(CLK_PRSC_2048, 15, 0);
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// no active bus session yet
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bus_claimed = 0;
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// Main menu
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for (;;) {
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neorv32_uart0_printf("TWI_EXPLORER:> ");
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length = neorv32_uart0_scan(buffer, 8, 1);
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neorv32_uart0_printf("\n");
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if (!length) // nothing to be done
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continue;
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// decode input and execute command
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if (!strcmp(buffer, "help")) {
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neorv32_uart0_printf("Available commands:\n"
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" help - show this text\n"
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" scan - scan bus for devices\n"
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" start - generate START condition\n"
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" stop - generate STOP condition\n"
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" send - write & read single byte to/from bus\n"
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" clock - configure bus clock (will reset TWI module!)\n"
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" stat - check if the TWI bus is currently claimed by any controller\n"
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" mack - enable/disable MASTER-ACK (ACK send by controller)\n\n"
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"Start a new transmission by generating a START condition. Next, transfer the 7-bit device address\n"
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"and the R/W flag. After that, transfer your data to be written or send a 0xFF if you want to read\n"
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"data from the bus. Finish the transmission by generating a STOP condition.\n\n");
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}
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else if (!strcmp(buffer, "start")) {
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neorv32_twi_generate_start(); // generate START condition
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bus_claimed = 1;
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}
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else if (!strcmp(buffer, "stop")) {
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if (bus_claimed == 0) {
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neorv32_uart0_printf("No active I2C transmission.\n");
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continue;
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}
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neorv32_twi_generate_stop(); // generate STOP condition
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bus_claimed = 0;
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}
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else if (!strcmp(buffer, "scan")) {
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scan_twi();
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}
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else if (!strcmp(buffer, "clock")) {
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set_clock();
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}
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else if (!strcmp(buffer, "send")) {
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if (bus_claimed == 0) {
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neorv32_uart0_printf("No active I2C transmission. Generate a START condition first.\n");
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continue;
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}
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else {
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send_twi();
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}
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}
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else if (!strcmp(buffer, "stat")) {
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check_claimed();
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}
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else if (!strcmp(buffer, "mack")) {
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toggle_mack();
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}
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else {
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neorv32_uart0_printf("Invalid command. Type 'help' to see all commands.\n");
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}
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}
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return 0;
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}
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/**********************************************************************//**
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* TWI clock speed menu
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**************************************************************************/
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void set_clock(void) {
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const uint32_t PRSC_LUT[8] = {2, 4, 8, 64, 128, 1024, 2048, 4096};
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char terminal_buffer[2];
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neorv32_uart0_printf("Select new clock prescaler (0..7; one hex char): ");
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neorv32_uart0_scan(terminal_buffer, 2, 1); // 1 hex char plus '\0'
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int prsc = (int)hexstr_to_uint(terminal_buffer, strlen(terminal_buffer));
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if ((prsc < 0) || (prsc > 7)) { // invalid?
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neorv32_uart0_printf("\nInvalid selection!\n");
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return;
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}
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neorv32_uart0_printf("\nSelect new clock divider (0..15; one hex char): ");
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neorv32_uart0_scan(terminal_buffer, 2, 1); // 1 hex char plus '\0'
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int cdiv = (int)hexstr_to_uint(terminal_buffer, strlen(terminal_buffer));
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neorv32_uart0_printf("\nEnable clock stretching (0=no, 1=yes)? ");
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neorv32_uart0_scan(terminal_buffer, 2, 1); // 1 hex char plus '\0'
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int csen = (int)hexstr_to_uint(terminal_buffer, strlen(terminal_buffer));
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// set new configuration
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neorv32_twi_setup(prsc, cdiv, csen);
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bus_claimed = 0;
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// print new clock frequency
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uint32_t clock = NEORV32_SYSINFO->CLK / (4 * PRSC_LUT[prsc] * (1 + cdiv));
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neorv32_uart0_printf("\nNew I2C clock: %u Hz\n", clock);
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}
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/**********************************************************************//**
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* Scan 7-bit TWI address space and print results
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**************************************************************************/
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void scan_twi(void) {
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neorv32_uart0_printf("Scanning TWI bus...\n");
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uint8_t i, num_devices = 0;
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for (i=0; i<128; i++) {
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uint8_t twi_ack = neorv32_twi_start_trans((uint8_t)(2*i+1));
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neorv32_twi_generate_stop();
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if (twi_ack == 0) {
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neorv32_uart0_printf(" + Found device at write-address 0x");
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print_hex_byte(2*i);
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neorv32_uart0_printf("\n");
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num_devices++;
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}
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}
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if (!num_devices) {
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neorv32_uart0_printf("No devices found.\n");
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}
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}
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/**********************************************************************//**
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* Check if the TWI is currently claimed.
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**************************************************************************/
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void check_claimed(void) {
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if (NEORV32_TWI->CTRL & (1 << TWI_CTRL_CLAIMED)) {
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if (bus_claimed == 0) {
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neorv32_uart0_printf("Bus claimed by another controller.\n");
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}
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else {
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neorv32_uart0_printf("Bus claimed by NEORV32 TWI.\n");
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}
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}
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else {
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neorv32_uart0_printf("Bus is idle.\n");
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}
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}
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/**********************************************************************//**
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* Toggle MACK (ACK generated by controller/host)
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**************************************************************************/
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void toggle_mack(void) {
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// toggle MACK flag
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NEORV32_TWI->CTRL ^= 1 << TWI_CTRL_MACK;
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if (NEORV32_TWI->CTRL & (1 << TWI_CTRL_MACK)) {
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neorv32_uart0_printf("MACK enabled.\n");
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}
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else {
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neorv32_uart0_printf("MACK disabled.\n");
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}
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}
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/**********************************************************************//**
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* Read/write menu to transfer 1 byte from/to bus
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**************************************************************************/
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void send_twi(void) {
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char terminal_buffer[4];
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// enter data
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neorv32_uart0_printf("Enter TX data (2 hex chars): ");
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neorv32_uart0_scan(terminal_buffer, 3, 1); // 2 hex chars for address plus '\0'
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uint8_t tmp = (uint8_t)hexstr_to_uint(terminal_buffer, strlen(terminal_buffer));
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uint8_t res = neorv32_twi_trans(tmp);
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neorv32_uart0_printf("\n RX data: 0x");
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print_hex_byte((uint8_t)neorv32_twi_get_data());
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neorv32_uart0_printf("\n Response: ");
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if (res == 0)
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neorv32_uart0_printf("ACK\n");
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else
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neorv32_uart0_printf("NACK\n");
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}
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/**********************************************************************//**
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* Helper function to convert N hex chars string into uint32_t
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*
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* @param[in,out] buffer Pointer to array of chars to convert into number.
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* @param[in,out] length Length of the conversion string.
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* @return Converted number.
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**************************************************************************/
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uint32_t hexstr_to_uint(char *buffer, uint8_t length) {
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uint32_t res = 0, d = 0;
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char c = 0;
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while (length--) {
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c = *buffer++;
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if ((c >= '0') && (c <= '9'))
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d = (uint32_t)(c - '0');
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else if ((c >= 'a') && (c <= 'f'))
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d = (uint32_t)((c - 'a') + 10);
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else if ((c >= 'A') && (c <= 'F'))
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d = (uint32_t)((c - 'A') + 10);
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else
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d = 0;
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res = res + (d << (length*4));
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}
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return res;
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}
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/**********************************************************************//**
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* Print byte as hex chars via UART0.
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*
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* @param data 8-bit data to be printed as two hex chars.
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**************************************************************************/
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void print_hex_byte(uint8_t data) {
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static const char symbols[] = "0123456789abcdef";
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neorv32_uart0_putc(symbols[(data >> 4) & 15]);
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neorv32_uart0_putc(symbols[(data >> 0) & 15]);
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}
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