![]() NOTE that you can JUST BRIDGE THE 3 PINS TOGETHER ( #48, #49#50) without cutting anything, however you need to make sure that the pins 49(PD6) and 50(PD7) are always defined as inputs :ĭDRD |= (0 << PD6)|(0<<PD7) //sets pins as inputsīEWARE though, if any of the PD5, PD6 or PD7 is defined as output and low while any other is high, it will short them! take a look at digital pin 38, (pin #50, (PD7) at the corner of the chip), it is only 1 pin away from the XCK1 pin ( #48 (PD5)). However, some of the functionality of theĬontrol registers changes when using MSPIM." The I/O register locations are the same in both modes. However, the pin control logic and interrupt generation logic is identical in The USART RX and TX control logic is replaced by a common SPI The parity generator and checker, the data and clock recovery logic, and the RX and TXĬontrol logic is disabled. Resources include the transmitter and receiver shift register and buffers, and the baud rate generator. The SPI master control logic takes direct control over the USART resources. Setting both UMSELn1:0 bits to one enables the USART in MSPIM logic. LSB First or MSB First Data Transfer (Configurable Data Order).Supports all four SPI Modes of Operation (Mode 0, 1, 2, and 3).Full Duplex, Three-wire Synchronous Data Transfer.The Master SPI Mode (MSPIM) has the following Set to a master SPI compliant mode of operation. The Universal Synchronous and Asynchronous serial Receiver and Transmitter (USART) can be I don't know if there is a library for this. With a 2560, you can also use the USART as SPI, so you can have 2 SPI ports. You would connect the two displays in parallel to MISO-MOSI-SCK and send data to one or the other using separate slave select for each one. You can do things like add wires from the 50-51-52 (or 51-52-53) pins to other pins to access them, and treat the new pins as inputs only in the sketch so there is no interference. Mega dig.SPI comes from dedicated internal hardware, so it can't be re-assigned. Uno port/pin : PD7 PD6 PD5 PD4 PD3 PD2 PB1 PB0 (see procedure Lcd_Writ_Bus ) Breakout/Arduino UNO pin usage: It's just pure self-contained code that goes right onto the bare metal, and does everything to drive the display, from initialization to filling the screen with a colour.Īnd it does put the data1,0 bits in PH6,5 as I had expected. Here is a dead simple sketch with no libraries, no classes and uses no other code. Upon further investigation, I'm pretty sure that the UTFT code above is wrong. I would be grateful if someone can explain this apparent contradiction. Obviously the code does work, and I'm just not seeing something. So how can this work? Those 2 bits should go to PH6,5 not PE1,0.įurthermore, PE1,0 are used for TXD and RXD, so those bits can't be used for the display. The shield uses the D9 and D8 pins for these bits, but they are connected to PH6 and PH5. This makes sense except for the two least significant data bits, which the code above is setting into port bits PE1 and PE0. ![]() This is done in the UTFT library for the MEGA board, using this code:. Therefore, code that writes to these shields must splatter the data bits to the appropriate AVR port bits, before strobing the shield's WR line. These pins don't connect to a single AVR 8 bit port, but are split amongst 2 or 3 ports. On these shields, the 8 data lines for bits 7.0 connect to Arduino pins D7.D2,D9,D8 on both UNO and MEGA. I'm experimenting with TFT LCD display shields designed for UNOs, but which can alsoīe used with the MEGA 2560 board, and I'm confused by an apparent contradiction. ![]()
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