--- title: "\"Sn_TX_RD\", \"Sn_TX_WR\" and \"Sn_TX_FSR\" reading problem [W5500]" url: "https://maker.wiznet.io/forum/13703" markdown_url: "https://maker.wiznet.io/forum/13703/md" type: "Forum topic" category: "Ethernet Chips" author: "e sh" created: "2020-02-14T12:11:06+09:00" last_activity: "2020-06-06T17:53:25+09:00" language: "en" views: 1302 replies: 9 source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)" --- # "Sn_TX_RD", "Sn_TX_WR" and "Sn_TX_FSR" reading problem [W5500] ## Question Asked by e sh on 2020-02-14 in Ethernet Chips. Hello. Before any question excuse me for my English. My language isn’t English. I want to write a simple test code for W5500 with Arduino Due. W5500 works as a client and my PC works as a server. The code saves a character in TX buffer and sends it to my PC. My code performs the following tasks: - loading common registers with appropriate values - opening the socket0 in TCP mode - connecting to server until here all things are perfect, but when i run send command (Sn_CR=0x20), the server receives arbitrary bytes. I perform updating process of Sn_TX_WR with respect to data sheet. Also, according to W5500 data sheet after connecting to server in TCP mode, the value of Sn_TX_RD and Sn_TX_WR will be re-initialized to 0x0000. But when i read these registers after connect command (Sn_CR=0x04), W5500 returns arbitrary numbers for both and these values are same for these registers. Also the value of Sn_TX_FSR reads as 0X0800 which is correct. When i read these registers after send command (Sn_CR=0x20), W5500 returns 0x0000 for Sn_TX_WR and Sn_TX_RD and an arbitrary number for Sn_TX_FRS. I don’t know where is the problem. Can anyone help me??? Thanks in advance. ## Replies ### Reply 1 by Mxyxixptlick, 2020-02-15 What software is acting as a server on your PC, and how do you know the problem isn’t there? ### Reply 2 by e sh, 2020-02-15 (in reply to reply 1) The problem solved! A little mistake in writing to tx buffer. But i wondering why W5500 returns an arbitrary numbers for Sn_TX_RD and Sn_Tx_WR registers after connecting to server? Server software on pc is a simple c code downloaded from internet and has been tested. Thanks for your reply. ### Reply 3 by Dan1, 2020-06-03 Hi, I have same problem now…! When sending string to a server I get a lot of “garbage” with the string. Reading **getSn_TX_FSR** before sending give 800h (2048) as expected but after sending the value is “strange” and not what I expect (2048 - string lengh)… What was the writing mistake? can you share it? Any Idea? Dan Groswirth [cellkey.tech.gmail.com](http://cellkey.tech.gmail.com) ### Reply 4 by e sh, 2020-06-03 (in reply to reply 3) Hello Dan1. I done the following steps to send data to my pc: 1- Reading start address of free space of TX buffer (Sn_TX_RD0 & Sn_TX_RD1). 2- Writing data to socket0 TX buffer in address which reads from previous step. 3- Updating S0_TX_WR register as follow: ``` S0_TX_WR = S0_TX_RD0 * 256 + S0_TX_RD1 + data_size ``` 4- Running socket send command. I hope this be useful. I will be glad if i can help you. ### Reply 5 by cellkey, 2020-06-03 Hello e_sh: Thanks for your response. The way you suggest to update pointer is not documented as far as I know. I have not seen it in any of the examples I have seen. Dont understand the " (Sn_TX_RD0 & Sn_TX_RD1)" that you mentioned. I use Sn_Tx_WR to get the pointer to writing location, as done at the send() rutine in socket.c file. Please explain your idea . Thanks Dan ### Reply 6 by e sh, 2020-06-04 (in reply to reply 5) hi I wrote my code without any library hence i manipulate registers directly. According to datasheet “Sn_TX_RD0 & Sn_TX_RD1” are high byte and low byte of pointer, respectively. More details on what i do: I read the registers 0x0022 and 0x0023 in socket register block. These registers indicate the start address for writing your data in TX buffer. Then i saved my data (for testing purpose i saved chatacter ‘a’) in TX buffer at address “Sn_TX_RD”. After these the Sn_TX_WR pointer must be updated as i mentioned in previous post. finally i issued the send command. what i discribed is mentioned in pages 54 and 55 of W5500 datasheet version1.0.9. Following is the piece of code related to these steps: ``` //Reading start address of free space of TX buffer PIOA->PIO_CODR = 1 << SS_PIN; // select slave SPI_transfer(0x00);//address SPI_transfer(0x22);//address SPI_transfer(0b00001000);//control S0_TX_RD_0 = SPI_transfer(0x00);//data S0_TX_RD_1 = SPI_transfer(0x00);//data PIOA->PIO_SODR = 1 << SS_PIN; // deselect slave //Writing data to socket0 TX buffer PIOA->PIO_CODR = 1 << SS_PIN; // select slave SPI_transfer(S0_TX_RD_0);//address SPI_transfer(S0_TX_RD_1);//address SPI_transfer(0b00010100);//control SPI_transfer('a');//data PIOA->PIO_SODR = 1 << SS_PIN; // deselect slave //Updating S0_TX_WR register data_size = 1; S0_TX_WR = S0_TX_RD_0 * 256 + S0_TX_RD_1 + data_size; PIOA->PIO_CODR = 1 << SS_PIN; // select slave SPI_transfer(0x00);//address SPI_transfer(0x24);//address SPI_transfer(0b00001100);//control SPI_transfer((S0_TX_WR >> 8) & 0xFF);//data SPI_transfer(S0_TX_WR & 0xFF);//data PIOA->PIO_SODR = 1 << SS_PIN; // deselect slave //Socket0 sending PIOA->PIO_CODR = 1 << SS_PIN; // select slave SPI_transfer(0x00);//address SPI_transfer(0x01);//address SPI_transfer(0b00001100);//control SPI_transfer(0x20);//data PIOA->PIO_SODR = 1 << SS_PIN; // deselect slave ``` Best regards. ### Reply 7 by Dan1, 2020-06-04 Hello e_sh: Thanks again for your support. I am getting into your code in order to understand the lower level of the handling of the appropriate registers… You read TX_RD to set the writing address while W5500 library show reading TX_WR as in that code: //writing data to TX buffer void wiz_send_data(uint8_t sn, uint8_t *wizdata, uint16_t len) { uint16_t ptr = 0; uint32_t addrsel = 0; if(len == 0) return; ptr = getSn_TX_WR(sn); //<<<<<<setting the pointer addrsel = ((uint32_t)ptr << 8) + (WIZCHIP_TXBUF_BLOCK(sn) << 3); WIZCHIP_WRITE_BUF(addrsel,wizdata, len); ptr += len; setSn_TX_WR(sn,ptr); } I still confused about handling the TX_WR and TX_RD pointers as I have problem that data I send is seen on server wrapped by “endless” garbage bytes and written several times… Regards Dan ### Reply 8 by e sh, 2020-06-04 Hi Dan1. Yes. The code is written for W5500. According to description of Sn_TX_RD in datasheet (page 54): > SEND command transmits the saved data from the current Sn_TX_RD to the Sn_TX_WR in the socket n TX buffer. After transmitting the saved data, the SEND command increases the Sn_TX_RD as same as the Sn_TX_WR. Hence, i think in the “wiz_send_data” routine, at line : > ptr = getSn_TX_WR(sn); //<<<<<<setting the pointer the Sn_TX_RD and Sn_TX_WR registers have the same value. Are you sure about your code on server side? Thank you. ### Reply 9 by cellkey, 2020-06-06 (in reply to reply 8) Hi: Thanks, a little late… I got it now alright. I have read both pointer at every step and learnt the way it treated… Regards Dan --- Source: https://maker.wiznet.io/forum/13703