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STV9420 bảng dữ liệu(PDF) 6 Page - STMicroelectronics |
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STV9420 bảng dữ liệu(HTML) 6 Page - STMicroelectronics |
6 / 16 page FUNCTIONAL DESCRIPTION The STV9420/21 display processor operation is controlled by a host MCU via the I 2C interface. It is fully programmable through 8 internal read/write registers (12 for STV9421) and performs all the display functions by generating pixels from data stored in its internal memory. After the page down- loading from the MCU, the STV9420/21 refreshes screen by its built in processor, without any MCU control (access).In addition, the host MCU has a direct access to the on chip 1Kbytes RAM during the display of the current page to make any update of its contents. With the STV9420/21, a page displayed on the screen is made of several strips which can be of 2 types : spacing or character and which are de- scribed by a table of descriptors and character codes in RAM. Several pages can be downloaded at the same time in the RAM and the choice of the current display page is made by programming the CONTROL register. I - Serial Interface The 2-wires serial interface is an I 2C interface. To be connected to the I 2C bus, a device must own its sl ave ad dr ess ; the sla ve address of t he STV9420/21 is BA (in hexadecimal). A6 A5 A4 A3 A2 A1 A0 R/W 10111 01 I.1 - Data Transfer in Write Mode The host MCU can write data into the STV9420/21 registers or RAM. To write data into the STV9420/21, after a start, the MCU must send (Figure 3) : - First, the I 2C address slave byte with a low level for the R/W bit, - The two bytes of the internal address where the MCU wants to write data(s), - The successive bytes of data(s). All bytes are sent MS bit first and the write data transfer is closed by a stop. I.2 - Data Transfer in Read Mode The host MCU can read data from the STV9420/21 registers, RAM or ROM. To read data from the STV9420/21 (Figure 4), the MCU must send 2 different I 2C sequences. The first one is made of I 2C slave address byte with R/W bit at low level and the 2 internal address bytes. The second one is made of I 2C slave address byte with R/W bit at high level and all the successive data bytes read at successive addresses starting from the initial address given by the first sequence. SCL SDA R/W A7 A6 A5 A4 A3 A2 A1 A0 I1C Slave Address ACK LSB Address ACK MSB Address ACK Start - - A13 A12 A10 A10 A9 A8 Stop SCL SDA R/W D7 D6 D5 D4 D3 D2 D1 D0 I1C Slave Address ACK ACK Data Byte n ACK Start D7 D6 D5 D4 D3 D2 D1 D0 Stop Data Byte 1 Figure 4 : STV9420/I 2C Read Operation SCL SDA R/W A7 A6 A5 A4 A3 A2 A1 A0 - - A13 A12 A11 A10 A9 A8 I2C Slave Address ACK LSB Address ACK MSB Address ACK Start D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 ACK ACK Data Byte 1 Data Byte 2 ACK Data Byte n Stop SCL SDA Figure 3 : STV9420/I 2C Write Operation STV9420 - STV9421 6/16 |
Số phần tương tự - STV9420 |
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Mô tả tương tự - STV9420 |
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