OV7620 SCCB keeps not receiving a response signal

You take a look at the following paragraph from my profile, it may be enlightening to you, and yours is a matter of specific development, so you should take a look first:

The control of the OV7620 adopts the Seriai Camera ControlBus (SCCB) protocol. SCCB is a simplified I2C protocol, SIO-L is a serial clock input line, SIO-O is a serial bidirectional data line, which is equivalent to the SCL of the I2C protocol and the bus timing is basically the same as I2C, and its response signal ACK is called the 9th bit of a transmission unit, which is divided into don't care and care bit generated by the slave; The Na bit is generated by the host and must be high because the SCCB does not support multi-byte reads and writes. In addition, SCCB does not have the concept of repeating the start, so during the read cycle of SCCB, when the host has finished sending the on-chip register address, it must send a bus stop condition.

Otherwise, when sending a read command, the slave will not be able to produce a don't care response signal.

Due to some nuances between I2C and SCCB, GPIO is used to emulate the SCCB bus. The pins connected to the SCL are always set to the output mode, while the pins connected to the SDA dynamically change the input and output mode of the pins by setting the value of IODIR during data transmission. The write cycle of SCCB directly uses the write cycle timing of the I2C bus protocol. The read cycle of the SC-CB adds a bus stop condition.

The address of the OV7620 function register is 0x00 0x7c (many of which are reserved registers). By setting the corresponding registers, the OV7620 can be made to work in different modes. For example, to set the OV7620 to 16-bit output mode for continuous scanning and RGB raw data, you need to set the following settings:

i2csendbyte() is the write register function, the first parameter ov7620 is the chip address 0x42 defined by the macro, the second parameter is the on-chip register address, and the third parameter is the corresponding register setting.

Writes such as 24C08 are operations in which the chip takes about 10ms to refresh the E2ROM after obtaining the buffered data, storing it in the chip registers, and storing it in the chip register. During this time, 24c08 will not accept any external read and write requests.

You need to add a delay of more than 10ms after sending the stop signal. That is, the interval between the previous stop and the next start when EE2ROM data is written, at least 10ms.

You're doing the Freescale camera group, and the CPU bus is blocked when DMA, so there is no way to calculate and process, but the DMA speed is very fast, and the delay time is negligible.

You can follow the instructions first. Then look for the scanner and camera in the control panel. No additional software program is required.

A bunch of upstairs with rs232.

SCCB can be used as I2C, but it can't be fired in bursts. i2S is audio, and it has nothing to do with these two.

SCCB is a simplified I2C protocol, the bus timing of SCCB is basically the same as that of I2C, and its response signal ACK is called the 9th bit of a transmission unit, which is divided into don't care and the concept of no repeated start, so in the read cycle of SCCB, when the host finishes sending the on-chip register address, the bus stop condition must be sent. Otherwise, when sending a read command, the slave will not be able to produce a don't care response signal.

I2S is a bus standard developed by Philips for the transmission of audio data between digital audio devices. The I2S protocol specifies that the left channel information is transmitted when the level is high and the right channel information is transmitted at the low level.

I2C can be used to replace standard parallel buses and connect a variety of integrated circuits and functional modules.

If it's not the STM32 with a digital camera interface, I'll sell the OV7620 with FIFO, I've done it before, and the direct drive of the F1 series is very difficult, and the picture distortion is very serious.

Isn't there a lot of ** of this on the Internet?