# Documentation issues (GPIO IOF, UART1)
**URL:** https://forums.sifive.com/t/documentation-issues-gpio-iof-uart1/2646
**Category:** HiFive1 Rev B
**Created:** [July 18, 2019, 10:48am UTC](https://forums.sifive.com/t/documentation-issues-gpio-iof-uart1/2646 "2019-07-18T10:48:41Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@saiparan](https://forums.sifive.com/u/saiparan)
#### Post date: [July 18, 2019, 10:48am UTC](https://forums.sifive.com/t/documentation-issues-gpio-iof-uart1/2646/1 "2019-07-18T10:48:42Z")
Hello,
I would like to share two documentation issues I noticed while I was trying to connect a TFMini lidar via UART1 to a HiFive1 rev b board.
1. In Table 52 of FE310-G002 Manual (v19p04), IO\_FUNC\_EN and IO\_FUNC\_SEL registers are not included, while they are mentioned in Section 17.8.
2. According to Table 53 GPIO IOF Mapping, UART1\_RX is mapped to GPIO18. And, according to the HiFive1 rev b pinout (Figure 5 of HiFive1 rev b getting started guid), the gpio18 is mapped to the board’s pin 2. However, based on my testing, the rx pin is actually mapped to pin 7 (gpio 23) as I can read the lidar’s data from the pin 7, not pin 2.
On the other hand, when I use UART0 instead, I can read the lidar’s data from pin 0 (gpio 16) as described in the documents.
So, I believe either the chip datasheet’s gpio mapping or hifive1 board’s pinmap information is incorrect.
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### Author:  [@ickga](https://forums.sifive.com/u/ickga)
#### Post date: [November 26, 2020, 1:43pm UTC](https://forums.sifive.com/t/documentation-issues-gpio-iof-uart1/2646/2 "2020-11-26T13:43:41Z")
is this true? i’m having issues reading from both UART Rx lines simultaneously…
i thought i read data from UART1 Rx, but now that i’m trying to set them both up i start to doubt myself.
has anyone done this? do i have to turn off some basic configuration for this to work?