diff options
Diffstat (limited to '')
| -rw-r--r-- | src/twi.spec.ts | 176 |
1 files changed, 175 insertions, 1 deletions
diff --git a/src/twi.spec.ts b/src/twi.spec.ts index 4f57dc7..de7ceb8 100644 --- a/src/twi.spec.ts +++ b/src/twi.spec.ts @@ -191,7 +191,6 @@ describe('TWI', () => { // Step 4: wait for stop condition runInstructions(cpu, twi, 16); - console.log(cpu.data[16]); expect(twi.eventHandler.stop).toHaveBeenCalled(); runInstructions(cpu, twi, 16); @@ -201,5 +200,180 @@ describe('TWI', () => { runInstructions(cpu, twi, 16); expect(cpu.data[17]).toEqual(0x42); }); + + it('should successfully receive a byte from a slave', () => { + const { program } = asmProgram(` + ; register addresses + _REPLACE TWSR, 0xb9 + _REPLACE TWDR, 0xbb + _REPLACE TWCR, 0xbc + + ; TWCR bits + _REPLACE TWEN, 0x04 + _REPLACE TWSTO, 0x10 + _REPLACE TWSTA, 0x20 + _REPLACE TWEA, 0x40 + _REPLACE TWINT, 0x80 + + ; TWSR states + _REPLACE START, 0x8 ; TWI start + _REPLACE MT_SLAR_ACK, 0x40 ; Slave Adresss ACK has been received + _REPLACE MT_DATA_RECV, 0x50 ; Data has been received + _REPLACE MT_DATA_RECV_NACK, 0x58 ; Data has been received, NACK has been returned + + ; Send start condition + ldi r16, TWEN + sbr r16, TWSTA + sbr r16, TWINT + sts TWCR, r16 + + ; Wait for TWINT Flag set. This indicates that the START condition has been transmitted + call wait_for_twint + + ; Check value of TWI Status Register. Mask prescaler bits. If status different from START go to ERROR + lds r16, TWSR + andi r16, 0xf8 + ldi r18, START + cpse r16, r18 + jmp error ; only jump if r16 != r18 (START) + + ; Load SLA_R into TWDR Register. Clear TWINT bit in TWCR to start transmission of address + ; 0xa1 = Address 0x50, read mode (R/W bit set) + _REPLACE SLA_R, 0xa1 + ldi r16, SLA_R + sts TWDR, r16 + ldi r16, TWINT + sbr r16, TWEN + sts TWCR, r16 + + ; Wait for TWINT Flag set. This indicates that the SLA+W has been transmitted, and ACK/NACK has been received. + call wait_for_twint + + ; Check value of TWI Status Register. Mask prescaler bits. If status different from MT_SLA_ACK go to ERROR + lds r16, TWSR + andi r16, 0xf8 + cpi r16, MT_SLAR_ACK + brne error + + ; Clear TWINT bit in TWCR to receive the next byte, set TWEA to send ACK + ldi r16, TWINT + sbr r16, TWEA + sbr r16, TWEN + sts TWCR, r16 + + ; Wait for TWINT Flag set. This indicates that the DATA has been received, and ACK has been transmitted + call wait_for_twint + + ; Check value of TWI Status Register. Mask prescaler bits. If status different from MT_DATA_RECV go to ERROR + lds r16, TWSR + andi r16, 0xf8 + cpi r16, MT_DATA_RECV + brne error + + ; Validate that we recieved the desired data - first byte should be 0x66 + lds r16, TWDR + cpi r16, 0x66 + brne error + + ; Clear TWINT bit in TWCR to receive the next byte, this time we don't ACK + ldi r16, TWINT + sbr r16, TWEN + sts TWCR, r16 + + ; Wait for TWINT Flag set. This indicates that the DATA has been received, and NACK has been transmitted + call wait_for_twint + + ; Check value of TWI Status Register. Mask prescaler bits. If status different from MT_DATA_RECV_NACK go to ERROR + lds r16, TWSR + andi r16, 0xf8 + cpi r16, MT_DATA_RECV_NACK + brne error + + ; Validate that we recieved the desired data - second byte should be 0x77 + lds r16, TWDR + cpi r16, 0x77 + brne error + + ; Transmit STOP condition + ldi r16, TWINT + sbr r16, TWEN + sbr r16, TWSTO + sts TWCR, r16 + + ; Wait for TWINT Flag set. This indicates that the STOP condition has been sent + call wait_for_twint + + ; Check value of TWI Status Register. The masked value should be 0xf8 once done + lds r16, TWSR + andi r16, 0xf8 + cpi r16, 0xf8 + brne error + + ; Indicate success by loading 0x42 into r17 + ldi r17, 0x42 + + loop: + jmp loop + + ; Busy-waits for the TWINT flag to be set + wait_for_twint: + lds r16, TWCR + andi r16, TWINT + breq wait_for_twint + ret + + ; In case of an error, toggle a breakpoint + error: + break + `); + const cpu = new CPU(program); + const twi = new AVRTWI(cpu, twiConfig, FREQ_16MHZ); + twi.eventHandler = { + start: jest.fn(), + stop: jest.fn(), + connectToSlave: jest.fn(), + writeByte: jest.fn(), + readByte: jest.fn() + }; + + // Step 1: wait for start condition + runInstructions(cpu, twi, 4); + expect(twi.eventHandler.start).toHaveBeenCalledWith(false); + + runInstructions(cpu, twi, 16); + twi.completeStart(); + + // Step 2: wait for slave connect in read mode + runInstructions(cpu, twi, 16); + expect(twi.eventHandler.connectToSlave).toHaveBeenCalledWith(0x50, false); + + runInstructions(cpu, twi, 16); + twi.completeConnect(true); + + // Step 3: send the first byte to the master, expect ack + runInstructions(cpu, twi, 16); + expect(twi.eventHandler.readByte).toHaveBeenCalledWith(true); + + runInstructions(cpu, twi, 16); + twi.completeRead(0x66); + + // Step 4: send the first byte to the master, expect nack + runInstructions(cpu, twi, 16); + expect(twi.eventHandler.readByte).toHaveBeenCalledWith(false); + + runInstructions(cpu, twi, 16); + twi.completeRead(0x77); + + // Step 5: wait for stop condition + runInstructions(cpu, twi, 24); + expect(twi.eventHandler.stop).toHaveBeenCalled(); + + runInstructions(cpu, twi, 16); + twi.completeStop(); + + // Step 6: wait for the assembly code to indicate success by settings r17 to 0x42 + runInstructions(cpu, twi, 16); + expect(cpu.data[17]).toEqual(0x42); + }); }); }); |