Hdmi-Cec Registers; Cec Control Register (Cec_Cr) - STMicroelectronics STM32F05 series Reference Manual

RM0091
28.7

HDMI-CEC registers

Refer to
28.7.1

CEC control register (CEC_CR)

Address offset: 0x00
Reset value: 0x0000 0000
31 30 29
Res. Res. Res. Res.
15 14 13
Res. Res. Res. Res.
Bits 31:3 Reserved, must be kept at reset value.
Bit 2 TXEOM: Tx End Of Message
The TXEOM bit is set by software to command transmission of the last byte of a CEC message.
TXEOM is cleared by hardware at the same time and under the same conditions as for TXSOM.
0: TXDR data byte is transmitted with EOM=0
1: TXDR data byte is transmitted with EOM=1
Note: TXEOM must be set when CECEN=1
TXEOM must be set before writing transmission data to TXDR
If TXEOM is set when TXSOM=0, transmitted message will consist of 1 byte (HEADER) only
(PING message)
Bit 1 TXSOM: Tx Start Of Message
TXSOM is set by software to command transmission of the first byte of a CEC message. If the CEC
message consists of only one byte, TXEOM must be set before of TXSOM.
Start-Bit is effectively started on the CEC line after SFT is counted. If TXSOM is set while a message
reception is ongoing, transmission will start after the end of reception.
TXSOM is cleared by hardware after the last byte of the message is sent with a positive acknowledge
(TXEND=1), in case of transmission underrun (TXUDR=1), negative acknowledge (TXACKE=1), and
transmission error (TXERR=1). It is also cleared by CECEN=0. It is not cleared and transmission is
automatically retried in case of arbitration lost (ARBLST=1).
TXSOM can be also used as a status bit informing application whether any transmission request is
pending or under execution. The application can abort a transmission request at any time by clearing
the CECEN bit.
0: No CEC transmission is on-going
1: CEC transmission command
Note: TXSOM must be set when CECEN=1
TXSOM must be set when transmission data is available into TXDR
HEADER's first four bits containing own peripheral address are taken from TXDR[7:4], not from
CEC_CFGR.OAR which is used only for reception
Section 1.1 on page 34
28 27 26 25
Res. Res. Res.
12 11 10 9
Res. Res. Res.
Doc ID 018940 Rev 1
for a list of abbreviations used in register descriptions.
24 23 22
Res. Res. Res.
8 7 6
Res. Res. Res.
HDMI-CEC controller (HDMI-CEC)
21 20 19 18
Res. Res. Res. Res.
5 4 3 2
TX
Res. Res. Res.
EOM
rs
17 16
Res. Res.
1 0
TX CEC
SOM ON
rs rw
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