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Firmware is a program that provides low-level control for a device's specific hardware. It performs control, monitoring and data manipulation functions. Firmware is stored in non-volatile memory like EPROM or flash memory. Common reasons for updating firmware include fixing bugs or adding new features. Firmware may be the only program that runs on an embedded system and provides all of its functions.
![The sequence the encoder outputs while spinning clockwise is 00, 01, 11, 10 repeat. So if you have a reading of 01,
the next reading can either be 00 or 11 depending on the direction the knob is turned. So by adding the previous
encoded value to the beginning of the current encoded value we get: [BEFORE(BA)+CURRENT(BA)]
CW: 0001(1H), 0111(7H), 1110(0EH), 1000(8H)
CCW: 1011(0BH), 1101(0DH), 0100(4H), 0010(2H)
Assembly Programming
11](https://image.slidesharecdn.com/assembler4-180222182324/85/Assembler4-13-320.jpg)
Assembler4
- 1. Chapter 4 Assembly Programming III Firmware is a program that provides the low-level control for the device's specific hardware, performing all control, monitoring and data manipulation functions. Typical examples of devices containing firmware are embedded systems, consumer appliances, computers, computer peripherals, and others. Firmware is held in non-volatile memory devices such as EPROM, or flash memory. Common reasons for updating firmware include fixing bugs or adding features to the device, then the flash memory is reprogrammed. Firmware such as the program of an embedded system may be the only program that will run on the system and provide all of its functions.
- 2. Assembly Programming………………….…………….…….………. 1 I2C Communication……….…………….…………….…….………. 1 Switch/Led……….…………………….…………….…….………. 4 32-bit Math……….…………………….…………….…….……….6 SPI Protocol……….…………………….…………….…….……….7 IR Remote Control: SIRC Protocol ……….…………………….………. 8 Power Supply Monitor ……….…………………..………….………. 9 Watchdog Timer ……….…………………..………….……..……. 10 Rotary Encoder ……….…………………..…….…….……..……. 10
- 3. I2C communication is initiated by the master sending a START condition and terminated by the master sending a STOP condition. A high-to-low transition on the SDA line while the SCL is high defines a START condition. A low-to- high transition on the SDA line while the SCL is high defines a STOP condition. One data bit is transferred during each clock pulse of the SCL. One byte is comprised of eight bits on the SDA line. Data is transferred Most Significant Bit (MSB) first. Data on the SDA line must remain stable during the high phase of the clock period, as shows below Each byte of data (including the address byte) is followed by one ACK bit from the receiver. The ACK bit (SDA “0” in 9 CLK high pulse) allows the receiver to communicate to the transmitter that the byte was successfully received I2C Communication Assembly Programming 1 Stop Bit Bit Start SCL SDA 1 2 3 4 5 6 7 8 9 ACK
- 4. The following program uses the I2C communication to send a character to a display (NEWHAVEN, NHD‐0420D3Z‐ NSW‐BBW‐V3) Assembly Programming 2
- 5. To read from a slave, the master must first instruct the slave which register it wishes to read from. This is done by the master starting off the transmission in a similar fashion as the write, by sending the address with the R/W bit equal to 0, followed by the register address it wishes to read from. Once the slave acknowledges this register address, the master will send a START condition again, followed by the slave address with the R/W bit set to 1. This time, the slave will acknowledge the read request, and the master releases the SDA bus, so that the slave can transmit data. The master will continue supplying the clock to the slave. At the end of every byte of data, the master will send an ACK to the slave, Once the master has received the number of bytes it is expecting, it will send a NACK, signaling to the slave to halt communications and release the bus. The master will follow this up with a STOP condition. The following program shows how to read a byte The following waveforms shows the process of programming the 16-Bit I/O Expander with I2C Interface: MCP-23017. ACK ACKACK ACKStart Stop Slave Address: 42H IODIRA: 00H Port A: Output Port B: Input R/W=0 Assembly Programming 3
- 6. Writing to I2C: Sending 55H to Port A Reading from I2C: Getting value from Port B To attend a switch or button it is necessary to consider: ✓ Bounce time (10 msec) ✓ Press time (50 - 100 msec or greater) The pins of Ports 2 and 3 than have internal pull-ups must have 1s written to them, and in that state can be used as inputs. Two of the most common configurations of switch interface are shows below Switch/Led Assembly Programming Start Stop Slave Address: 42H Port A Address: 12H Value to Write: 55HACK ACK ACK R/W=0 R/W=0 ACK ACK ACK Slave Address: 42H Start Port B Address: 13H Start Slave Address: 43H R/W=1 Stop Read Value: 55H NACK 4
- 7. Response time of button, key or switch: SW1 (“1” active), SW2 (“0” active) Getting value from Port B Assembly Programming 5
- 8. 16-bit and 32-bit math routines can be used to extend the calculation capacity of the microcontroller, the most popular is the Application Brief AB-40 from INTEL. The 32-bit Math Routines can be useful to calculate equations in floating-point using equivalent calculation in fixed-point. The fundamental routines are: MUL_16, DIV_16, ADD_16, SUB_16, ADD_32, SUB_32. Fixed Point Arithmetic The Internal Temperature Sensor of ADuC842 has a voltage output of 700mV at 250C, with a variation of -1.4mV/0C. The Equivalent Voltage of a Hexadecimal Code in an ADC (12 bits, Vref = 2.5V) is: Voltage = 2.5*HEXADECIMAL_CODE/2^12 Using the above relations, after some Math, we can obtain the temperature equivalent to a Hexadecimal Code: Temperature = 525 – 0.436*HEXADECIMAL_CODE In order to avoid the floating-point arithmetic, we can obtain an equivalent relation using integer values: Temperature = (5250000 – 4360*HEXADECIMAL_CODE)/1000 >> 525 - 0.436*Cod_Hex ans = 25.3440 >> (5250000-4360*Cod_Hex)/1000 ans = 253.4400 Temperature from ADC Principal Program Temperature Calculation (32-bit Math) 32-bit Math Assembly Programming 6
- 9. Serial Peripheral Interface (SPI) uses a four-wire serial bus: SS (Slave Select, Active Low): Specific to each slave. This is the pin that the SPI master use to enable the device. SCK (Serial Clock): The master generates the clock pulses that synchronize the data transmission. MOSI (Master Out Slave In) – This line is the master line for sending data to the SPI peripherals. MISO (Master In Slave Out) – This line is the slave line for sending data to the SPI master. Data Transmission (CPOL=0, CPHA=0): 1.- The master selects the slave by setting the SS pin of slave to low (SCK must be low). 2.- The master sends a bit on MOSI line and the slave reads it on the clock's low-to-high transition. The slave also sends a bit on the MISO line on the falling edge of the SCK, so that the data would be stable when read by the master on rising edges of SCK. 3.- When the transfer is complete, the master stops toggling the SCK and mostly pulls up the SS to deselect the slave. SPI Protocol Transferring 0A5H (MSB first) Assembly Programming SCK SS MOSI MISO MSB LSB 7
- 10. Then, a new high to low transition is waited to detect the first bit. The value of a bit is sample each 900usec. In the 12 bits SIRC version, each word is sent LSB first as shown bellow The frames are repeated at an interval of 45msec, a minimum of 3 times. To assemble the input data, it’s necessary to wait the START pulse (high to low transition) and wait 2500usec IR Remote Control: SIRC Protocol S 0 1 2 3 4 5 6 0 1 2 3 4 8 1 Level Assembly Programming Start(5T) 0(2T)1(3T) Command (bits 0 - 6) Address (bits 0 - 4) T=0.6msec 0 Level
- 11. IR Remote tester in Password Protected System Fundamental functions used to test the IR Remote Controller (RCA RCRN03BR, programmed code: 10810) KEYS_IDENT (KEYS_ID.asm): Output of IR Remote Controller WRITE_FLASH (Write_Flash.asm): Write 4 digits to Internal Flash Memory READ_FLASH_PASS (Read_Passw.asm): Read 4 digits from Internal Flash Memory PASSW_CHECK (Pass_check.asm): Read 4 digits from IR Remote VERY_PASSW (Windows_1.asm): Verify the Password (Internal Flash vs IR Remote) PASSW_NEW (Pass_check.asm): Read 4 digits from IR Remote PASSW_VERY (Pass_check.asm): Verify the Password (Enter and New Password) PASSW_DEF_RUT (PASS_INIT.asm): Initial Password and Flag Press this link for more information The power supply monitor monitors the power supply on the Microconverter. It indicates when any of the supply pins drops below one of two user selectable voltage trip points, 2.93 V and 3.08 V. Monitor function is controlled via the PSMCON SFR. If enabled via the IEIP2 SFR, the monitor interrupts the core using the PSMI bit in the PSMCON SFR. This bit is not cleared until the failing power supply has returned above the trip point for at least 250 msec. This monitor function allows the user to save working registers to avoid possible data loss due to the low supply condition and ensures that normal code execution does not resume until a safe supply level has been well established. Power Supply Monitor Assembly Programming 9
- 12. The watchdog timer is a device that asserts a system reset or interrupt if it has not received a periodic pulse signal from a processor within a specific time frame. The processor periodically sends a pulse to the watchdog timer to indicate that the system software is operating properly. If the watchdog timer does not receive this pulse within an allotted time frame (known as the watchdog timeout), the watchdog timer asserts a reset. The watchdog timer is used to recover a microcontroller that has gone "out of control" due to power supply transients, electromagnetic interference, electrostatic discharge, etc. Incremental Rotary Encoders transduce rotational movement into electrical signals. If clockwise versus counterclockwise movement must be distinguished, two encoder outputs with a phase offset can accomplish this. Then the order of 2-bit states describes the direction turned, using a 90° phase offset (quadrature). Based on the feature size of an encoder, it can produce a different number of output states per revolution. When the quadrature encoder is rotating in a clockwise direction its signal will show Channel A leading Channel B, and the reverse will happen when the quadrature encoder rotates counterclockwise. The rotary Encoder may have a built-in switch Watchdog Timer Rotary Encoder Assembly Programming 10 De-Bounced BA=00 BA=01 BA=11 BA=10
- 13. The sequence the encoder outputs while spinning clockwise is 00, 01, 11, 10 repeat. So if you have a reading of 01, the next reading can either be 00 or 11 depending on the direction the knob is turned. So by adding the previous encoded value to the beginning of the current encoded value we get: [BEFORE(BA)+CURRENT(BA)] CW: 0001(1H), 0111(7H), 1110(0EH), 1000(8H) CCW: 1011(0BH), 1101(0DH), 0100(4H), 0010(2H) Assembly Programming 11