神农鼎
发表于 2024-6-28 14:21:16
RS485自动收发切换
xxkj2010
发表于 2024-7-4 11:20:18
现在兑换区有8引脚的STC8H2K12U了，拿来做转串口，真的很好！{:4_250:}
jmg
发表于 2024-7-7 07:46:32
本帖最后由 jmg 于 2024-7-8 09:41 编辑
神农鼎 发表于 2024-6-28 14:21
RS485自动收发切换
This PNP auto direction change works quite well, and is simple.
It should be checked with the RS485 IC chosen, as there are caveats :
a) TX Enable (PNP turning ON) needs to be fast enough to not distort the bit-timing.
b) RX Enable (PNP turning OFF) needs to be slow enough to allow the BUS driver to change before the RX enable, otherwise you get a RXD glitch.
A PNP driver works well because it has skewed ON and OFF times. (NPN skews the wrong way)
LTspice has FAST (20MBd) RS485 LTC2862-1 and SLOW(250kBd) RS485 LTC2862-2 models so you can check the effect in LTSpice.
Digital Transistors (eg DTA014T)include the 10k base resistor, and simulates Trelease = 1.234usTenable = 47.4ns, which is enough for up to 1-2 MBd region.
For very high baud rates, (3~11.25Mbd+) the base resistor value can drop, or you can switch to a low capacitance PMOS part like BSS84, or a Analog Sw like x3157, or Logic Gate like x1G125, can emulate a Low-C PMOS.
giveyou
发表于 2024-11-8 15:13:08
{:4_165:}{:4_165:}
是三三啊
发表于 2024-12-16 17:11:35
<p>这个和AI8H2K08U模拟的有什么区别啊</p>
q342698102
发表于 2025-3-2 11:09:26
楼主STC USB-2UART-45I-SOP16芯片手册可以共享一下吗？
q342698102
发表于 2025-3-2 11:18:28
想要做一个单纯的USB转232的数据线，按照这个原理图来做就可以了吗
神农鼎
发表于 2025-3-2 11:47:32
q342698102 发表于 2025-3-2 11:09
楼主STC USB-2UART-45I-SOP16芯片手册可以共享一下吗？
https://www.stcaimcu.com/data/download/Datasheet/STC8H.pdf
q342698102
发表于 2025-3-2 12:18:58
收到，谢谢您
q342698102
发表于 2025-3-12 21:40:53
成品出来了，可惜没有通讯上，使用买的成品usb转232线能收到数据 ，继续尝试中{:4_167:}