---
title: "Serial data output"
url: "https://maker.wiznet.io/forum/10729"
markdown_url: "https://maker.wiznet.io/forum/10729/md"
type: "Forum topic"
category: "Wireless"
author: "anglial"
created: "2014-12-15T14:09:43+09:00"
last_activity: "2017-05-04T08:34:32+09:00"
language: "en"
views: 429
replies: 3
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Serial data output

## Question

Asked by anglial on 2014-12-15 in Wireless.

We are trying to transfer data as fast as possible between 2 wizfi modules, using the uart.

We have observed that when the received data is written out of the wizfi uart at 3686400 baud, each byte takes 2.71 us to be written out (including start and stop bit), then the transmit line remains high for a further 5.5 us before the start bit of the next byte.

Therefore each byte takes 8.2 us in total, limiting it to 122,000 bytes per second.

If the host processor were to read the data out using SPI pins instead of the uart, could the data be read any faster ?

## Replies

### Reply 1 by ssekim, 2014-12-15

Hello anglial

I recommend UART regarding to high throughput.
As you know, SPI have no flow-control unlike UART(CTS/RTS), so in high frequency, there can be data loss.

And please refer to the below.

[url][http://wizwiki.net/wiki/doku.php?id=products:wizfi250:wizfi250pg:start#wizfi250_uart_throughput_test_report\[/url\]](http://wizwiki.net/wiki/doku.php?id=products:wizfi250:wizfi250pg:start#wizfi250_uart_throughput_test_report%5B/url%5D)

### Reply 2 by anglial, 2014-12-16

So is there any way of achieving a faster transfer rate ?

It is not a problem putting the data into the Wizfi which is transmitting (as test report showed), only in receiving it at the other end.

### Reply 3 by ssekim, 2014-12-16

Yes.
As I know, above result is WizFi250-best-throughput.

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Source: https://maker.wiznet.io/forum/10729