UART reading more than 8byte, how? - Page 1
Forum section: electronics / general

author: ulix
author_rank: Regular Contributor
timestamp: October 19, 2016, 05:08:24 pm
content: Hi,I want to send and read some AT Commands from a ESP8266 Modul with a NXP KL82Z Board.(I'm using Kinetis Design Studio and the SDK for KL82Z)Here is some example code, which I'm trying to edit. But I don't get it to read more than 8byte, for example when sending 12345678 it works. But when I get over 8 byte, the additional bytes are lost. I only got it to read it and then get stuck in code.How could I check if there is additional data?Code:#include "board.h"#include "fsl_lpuart.h"#include "pin_mux.h"#include "clock_config.h"/******************************************************************************** Definitions******************************************************************************/#define DEMO_LPUART LPUART0#define DEMO_LPUART_CLKSRC kCLOCK_PllFllSelClk#define DEMO_LPUART_IRQn LPUART0_IRQn#define DEMO_LPUART_IRQHandler LPUART0_IRQHandler/*! @brief Ring buffer size (Unit: Byte). */#define DEMO_RING_BUFFER_SIZE 16/*! @brief Ring buffer to save received data. *//******************************************************************************** Prototypes******************************************************************************//******************************************************************************** Variables******************************************************************************/uint8_t g_tipString[] ="Lpuart functional API interrupt example\r\nBoard receives characters then sends them out\r\nNow please input:\r\n";/*Ring buffer for data input and output, in this example, input data are savedto ring buffer in IRQ handler. The main function polls the ring buffer status,if there are new data, then send them out.Ring buffer full: (((rxIndex + 1) % DEMO_RING_BUFFER_SIZE) == txIndex)Ring buffer empty: (rxIndex == txIndex)*/uint8_t demoRingBuffer;volatile uint16_t txIndex; /* Index of the data to send out. */volatile uint16_t rxIndex; /* Index of the memory to save new arrived data. *//******************************************************************************** Code******************************************************************************/void DEMO_LPUART_IRQHandler(void){uint8_t data;/* If new data arrived. */if ((kLPUART_RxDataRegFullFlag)&LPUART_GetStatusFlags(DEMO_LPUART)){data = LPUART_ReadByte(DEMO_LPUART);/* If ring buffer is not full, add data to ring buffer. */if (((rxIndex + 1) % DEMO_RING_BUFFER_SIZE) != txIndex){demoRingBuffer = data;rxIndex++;rxIndex %= DEMO_RING_BUFFER_SIZE;}}}/*!* @brief Main function*/int main(void){lpuart_config_t config;BOARD_InitPins();BOARD_BootClockRUN();CLOCK_SetLpuartClock(1U);/** config.baudRate_Bps = 115200U;* config.parityMode = kLPUART_ParityDisabled;* config.stopBitCount = kLPUART_OneStopBit;* config.txFifoWatermark = 0;* config.rxFifoWatermark = 0;* config.enableTx = false;* config.enableRx = false;*/LPUART_GetDefaultConfig(&config);config.baudRate_Bps = BOARD_DEBUG_UART_BAUDRATE;config.enableTx = true;config.enableRx = true;LPUART_Init(DEMO_LPUART, &config, CLOCK_GetFreq(DEMO_LPUART_CLKSRC));/* Send g_tipString out. */LPUART_WriteBlocking(DEMO_LPUART, g_tipString, sizeof(g_tipString) / sizeof(g_tipString));/* Enable RX interrupt. */LPUART_EnableInterrupts(DEMO_LPUART, kLPUART_RxDataRegFullInterruptEnable);EnableIRQ(DEMO_LPUART_IRQn);while (1){/* Send data only when LPUART TX register is empty and ring buffer has data to send out. */while ((kLPUART_TxDataRegEmptyFlag & LPUART_GetStatusFlags(DEMO_LPUART)) && (rxIndex != txIndex)){LPUART_WriteByte(DEMO_LPUART, demoRingBuffer);txIndex++;txIndex %= DEMO_RING_BUFFER_SIZE;}}}Thank you, would be very thankful for any help.

author: cv007
author_rank: Frequent Contributor
timestamp: October 19, 2016, 05:43:02 pm
content: A quick look - seems to be wrongrxIndex %= DEMO_RING_BUFFER_SIZE;if (rxIndex==8)rxIndex=0;(probably forgot to remove those last 2 lines)

author: rstofer
author_rank: Super Contributor
timestamp: October 19, 2016, 06:22:06 pm
content: You can avoid the modulo arithmetic if your circular buffers have a length that is a binary multiple#define RING_LENGTH = 32#define RING_MASK = RING_LENGTH - 1ringptr = (ringptr + 1) & RING_MASK;

author: ulix
author_rank: Regular Contributor
timestamp: October 19, 2016, 06:37:07 pm
content: Quote from: cv007 on October 19, 2016, 05:43:02 pmYes, this was some try....

author: ulix
author_rank: Regular Contributor
timestamp: October 19, 2016, 08:14:18 pm
content: thanks rstofer, I got it working! Perfekt, thanks!

author: Bruce Abbott
author_rank: Frequent Contributor
timestamp: October 21, 2016, 07:42:17 pm
content: Quote from: rstofer on October 19, 2016, 06:22:06 pmBut why would you when modulo works inallcases, and generates the same machine code?source: -rxIndex++;rxIndex %= RING_BUFFER_SIZE;disassembly:-add r2, r2, #1and r2, r7source:-#define RING_MASK RING_BUFFER_SIZE-1rxIndex = (rxIndex + 1) & RING_MASK;disassembly:-add r2, r2, #1and r2, r7