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-rw-r--r--src/peripherals/usart.spec.ts136
1 files changed, 97 insertions, 39 deletions
diff --git a/src/peripherals/usart.spec.ts b/src/peripherals/usart.spec.ts
index 04e377b..2728f9c 100644
--- a/src/peripherals/usart.spec.ts
+++ b/src/peripherals/usart.spec.ts
@@ -22,6 +22,9 @@ const UDRIE = 0x20;
const TXCIE = 0x40;
const TXC = 0x40;
const UDRE = 0x20;
+const USBS = 0x08;
+const UPM0 = 0x10;
+const UPM1 = 0x20;
// Interrupt address
const PC_INT_UDRE = 0x26;
@@ -48,40 +51,87 @@ describe('USART', () => {
expect(usart.baudRate).toEqual(2400);
});
- it('should return 5-bits per byte when UCSZ = 0', () => {
- const cpu = new CPU(new Uint16Array(1024));
- const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
- cpu.writeData(UCSR0C, 0);
- expect(usart.bitsPerChar).toEqual(5);
- });
+ describe('bitsPerChar', () => {
+ it('should return 5-bits per byte when UCSZ = 0', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, 0);
+ expect(usart.bitsPerChar).toEqual(5);
+ });
- it('should return 6-bits per byte when UCSZ = 1', () => {
- const cpu = new CPU(new Uint16Array(1024));
- const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
- cpu.writeData(UCSR0C, UCSZ0);
- expect(usart.bitsPerChar).toEqual(6);
+ it('should return 6-bits per byte when UCSZ = 1', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, UCSZ0);
+ expect(usart.bitsPerChar).toEqual(6);
+ });
+
+ it('should return 7-bits per byte when UCSZ = 2', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, UCSZ1);
+ expect(usart.bitsPerChar).toEqual(7);
+ });
+
+ it('should return 8-bits per byte when UCSZ = 3', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, UCSZ0 | UCSZ1);
+ expect(usart.bitsPerChar).toEqual(8);
+ });
+
+ it('should return 9-bits per byte when UCSZ = 7', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, UCSZ0 | UCSZ1);
+ cpu.writeData(UCSR0B, UCSZ2);
+ expect(usart.bitsPerChar).toEqual(9);
+ });
});
- it('should return 7-bits per byte when UCSZ = 2', () => {
- const cpu = new CPU(new Uint16Array(1024));
- const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
- cpu.writeData(UCSR0C, UCSZ1);
- expect(usart.bitsPerChar).toEqual(7);
+ describe('stopBits', () => {
+ it('should return 1 when USBS = 0', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ expect(usart.stopBits).toEqual(1);
+ });
+
+ it('should return 2 when USBS = 1', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, USBS);
+ expect(usart.stopBits).toEqual(2);
+ });
});
- it('should return 8-bits per byte when UCSZ = 3', () => {
- const cpu = new CPU(new Uint16Array(1024));
- const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
- cpu.writeData(UCSR0C, UCSZ0 | UCSZ1);
- expect(usart.bitsPerChar).toEqual(8);
+ describe('parityEnabled', () => {
+ it('should return false when UPM1 = 0', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ expect(usart.parityEnabled).toEqual(false);
+ });
+
+ it('should return true when UPM1 = 1', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, UPM1);
+ expect(usart.parityEnabled).toEqual(true);
+ });
});
- it('should return 9-bits per byte when UCSZ = 7', () => {
- const cpu = new CPU(new Uint16Array(1024));
- const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
- cpu.writeData(UCSR0C, UCSZ0 | UCSZ1);
- cpu.writeData(UCSR0B, UCSZ2);
- expect(usart.bitsPerChar).toEqual(9);
+ describe('parityOdd', () => {
+ it('should return false when UPM0 = 0', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ expect(usart.parityOdd).toEqual(false);
+ });
+
+ it('should return true when UPM0 = 1', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0C, UPM0);
+ expect(usart.parityOdd).toEqual(true);
+ });
});
it('should invoke onByteTransmit when UDR0 is written to', () => {
@@ -93,21 +143,11 @@ describe('USART', () => {
expect(usart.onByteTransmit).toHaveBeenCalledWith(0x61);
});
- it('should set UDRE and TXC flags after UDR0', () => {
- const cpu = new CPU(new Uint16Array(1024));
- new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
- cpu.writeData(UCSR0B, TXEN);
- cpu.writeData(UCSR0A, 0);
- cpu.writeData(UDR0, 0x61);
- expect(cpu.data[UCSR0A]).toEqual(TXC | UDRE);
- });
-
describe('tick()', () => {
it('should trigger data register empty interrupt if UDRE is set', () => {
const cpu = new CPU(new Uint16Array(1024));
const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
cpu.writeData(UCSR0B, UDRIE | TXEN);
- cpu.writeData(0xc6, 0x61);
cpu.data[SREG] = 0x80; // SREG: I-------
usart.tick();
expect(cpu.pc).toEqual(PC_INT_UDRE);
@@ -121,9 +161,10 @@ describe('USART', () => {
cpu.writeData(UCSR0B, TXCIE | TXEN);
cpu.writeData(UDR0, 0x61);
cpu.data[SREG] = 0x80; // SREG: I-------
+ cpu.cycles = 1e6;
usart.tick();
expect(cpu.pc).toEqual(PC_INT_TXC);
- expect(cpu.cycles).toEqual(2);
+ expect(cpu.cycles).toEqual(1e6 + 2);
expect(cpu.data[UCSR0A] & TXC).toEqual(0);
});
@@ -143,9 +184,10 @@ describe('USART', () => {
cpu.writeData(UCSR0B, UDRIE | TXEN);
cpu.writeData(UDR0, 0x61);
cpu.data[SREG] = 0; // SREG: 0 (disable interrupts)
+ cpu.cycles = 1e6;
usart.tick();
expect(cpu.pc).toEqual(0);
- expect(cpu.cycles).toEqual(0);
+ expect(cpu.cycles).toEqual(1e6);
expect(cpu.data[UCSR0A]).toEqual(TXC | UDRE);
});
});
@@ -192,4 +234,20 @@ describe('USART', () => {
expect(usart.onLineTransmit).toHaveBeenCalledWith('there');
});
});
+
+ describe('integration', () => {
+ it('should set the TXC bit after ~1.04mS when baud rate set to 9600', () => {
+ const cpu = new CPU(new Uint16Array(1024));
+ const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
+ cpu.writeData(UCSR0B, TXEN);
+ cpu.writeData(UBRR0L, 103); // baud: 9600
+ cpu.writeData(UDR0, 0x48); // 'H'
+ cpu.cycles += 16000; // 1ms
+ usart.tick();
+ expect(cpu.data[UCSR0A] & TXC).toEqual(0);
+ cpu.cycles += 800; // 0.05ms
+ usart.tick();
+ expect(cpu.data[UCSR0A] & TXC).toEqual(TXC);
+ });
+ });
});
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