Ir Led And Ir Receiver; Usarts; Figure 7. Usart Data Flow - ST STM32091C-EVAL User Manual

UM1817
The CEC injector mode can be enabled by some PCB reworks for debugging purpose only:
•
Remove resistors R15, R17, R19, R28, R31, R35 and R38.
•
Close solder bridges SB2, SB3, SB4 and SB5.
Note: The I/O PD11 must be set in open-drain output mode by firmware when working as an HPD
signal control on the HDMI sink connector CN3.
2.18

IR LED and IR receiver

The IR receiver TSOP34836 is connected to PC6 of STM32F091VCT6 and a current
around 100mA on IR LED is driven by PB9 through transistors T4 and T5 on the board.
Note: the IR LED may be driven by PB9 directly with 20mA current when SB20 is closed and
R116 is removed.
2.19 8x USARTs
USART chain could be routed to a 2*8 header so that some jumpers could be used to
connect them in order to demonstrate 8 USART channels in daisy chain. The data flow is as
showed in the below picture:
USART1_TX
At the end both data sent at USART1_TX and data received at USART_RX can be
compared and validated thanks to USARTs chain on CN1.
Warning:

Figure 7. USART data flow

USART2_RX
USART2_TX USART3_RX
USART3_TX USART4_RX
USART4_TX
USART1/4/8 belongs to VDDIO2 power domain and
USART2/3/5/6/7 belongs to VDDIO power domain, so the
same voltage level for VDDIO and VDDIO2 is needed, to demo
USART chain application on this header.
DocID026902 Rev 2
Hardware Layout and configuration
USART5_RX
USART5_TX USART6_RX
USART6_TX USART7_RX
USART7_TX USART8_RX
USART8_TX USART1_RX
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