Fixup/document I2C
This commit is contained in:
Ondrej Jirman
parent
fbfa245ad4
commit
04ca071b09
124
firmware/main.c
124
firmware/main.c
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@ -341,51 +341,113 @@ void ext_int_deassert(void)
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#define I2C_N_REGS 16
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static uint8_t i2c_transfer = 0x00;
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static uint8_t i2c_addr = 0;
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static uint8_t i2c_regs[I2C_N_REGS] = {0xaa, 0x55};
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static uint8_t i2c_cmd[I2C_N_REGS];
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static uint8_t i2c_cmd_len = 0;
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static uint8_t i2c_rx_cnt = 0;
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static uint8_t i2c_tx_cnt = 0;
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static uint8_t i2c_tx_buf[I2C_N_REGS] = {0xaa, 0x55};
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static uint8_t i2c_rx_buf[I2C_N_REGS];
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//XXX: how to determine end of I2C transaction from the interrupt?
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//XXX: we need this to be able to determine when it's safe to go back to sleep/power down
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/*
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* Host write transaction: sending 01 02 03 04 to device at 0x15 (0x2a == 0x15 << 1)
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*
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* int=60 CR1=8c CR2=af DATA_PRE=2a rx
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* int=60 CR1=8e CR2=af DATA_PRE=01 rx
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* int=60 CR1=8e CR2=af DATA_PRE=02 rx
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* int=60 CR1=8e CR2=af DATA_PRE=03 rx
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* int=60 CR1=8e CR2=af DATA_PRE=04 rx
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* int=70 CR1=0c CR2=2f DATA_PRE=04 stop
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*
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* Host read transaction: receiving 4 bytes
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*
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* int=a0 CR1=8d CR2=af tx
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* int=a0 CR1=8d CR2=af tx
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* int=a0 CR1=8d CR2=af tx
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* int=a0 CR1=89 CR2=af tx
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* int=b0 CR1=08 CR2=2f stop
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*
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* CR1:
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* 7: STROBE/PEND (RX/TX: not set on stop IRQ, even though RXSF/TXSF is also set)
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* 3: SAR_EMPTY (RX/TX: always set)
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* 2: ACK (RX: always set)
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* (TX: set on all except on the last TX byte)
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* 1: FULL (RX: not set on first RX byte, which is a device address)
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* (TX: always not set)
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* 0: EMPTY (RX: always not set)
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* (TX: alwyas set except after stop IRQ)
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*
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* CR2:
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* 7: I2C busy flag (RX/TX: not set after stop IRQ)
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* 6: ?
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* 5: SW_RESET
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* 4: BBF
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*
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* I2CBINT:
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* 7: TXSF
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* 6: RXSF
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* 5: STP_IEN
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* 4: STOPF
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*
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* Powerdown is only possible after the stop bit. Wakeup only happens
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* on address match.
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*/
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#define I2C_ADDR 0x15
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#define I2C_DEBUG 0
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void i2c_b_interupt(void) __interrupt(IRQ_I2CB)
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{
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uint8_t saved_page = PAGESW;
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uint8_t tmp;
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PAGESW = 0;
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#if I2C_DEBUG
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puts("i2cb int=");
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put_hex_b(P0_I2CBINT);
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puts(" CR1=");
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put_hex_b(P0_I2CBCR1);
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puts(" CR2=");
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put_hex_b(P0_I2CBCR2);
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puts("\n");
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#endif
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// handle stop condition
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if (P0_I2CBINT & BIT(4)) {
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if (i2c_rx_cnt) {
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//XXX: process received data
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puts("I2C RX: ");
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for (uint8_t i = 0; i < i2c_rx_cnt; i++)
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put_hex_b(i2c_rx_buf[i]);
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puts("\n");
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}
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i2c_tx_cnt = 0;
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i2c_rx_cnt = 0;
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goto out_ack;
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}
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// handle TX
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if (P0_I2CBINT & BIT(7)) {
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if (i2c_addr < 16)
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P0_I2CBDB = i2c_regs[i2c_addr++];
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if (i2c_tx_cnt < I2C_N_REGS)
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P0_I2CBDB = i2c_tx_buf[i2c_tx_cnt++];
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else
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P0_I2CBDB = 0xff;
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P0_I2CBCR1 &= ~BIT(7); // clear data pending
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P0_I2CBINT &= ~BIT(7);
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goto out_ack;
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}
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// handle RX
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if (P0_I2CBINT & BIT(6)) {
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tmp = P0_I2CBDB;
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if (i2c_cmd_len < 16)
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i2c_cmd[i2c_cmd_len++] = tmp;
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uint8_t empty = P0_I2CBCR1 & BIT(1);
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uint8_t tmp = P0_I2CBDB;
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PAGESW = 0;
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if (empty && i2c_rx_cnt < I2C_N_REGS)
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i2c_rx_buf[i2c_rx_cnt++] = tmp;
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P0_I2CBCR1 &= ~BIT(7); // clear data pending
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P0_I2CBINT &= ~BIT(6);
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}
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// handle stop condition
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if (P0_I2CBINT & BIT(4)) {
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i2c_addr = 0;
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i2c_cmd_len = 0;
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P0_I2CBINT &= ~BIT(4);
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goto out_ack;
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}
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out_ack:
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P0_I2CBINT &= ~(BIT(4) | BIT(7) | BIT(6));
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P0_I2CBCR1 &= ~BIT(7); // clear data pending
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PAGESW = saved_page;
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}
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@ -409,7 +471,7 @@ void i2c_slave_init(void)
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// setup I2C address
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P0_I2CBDAH = 0x00;
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P0_I2CBDAL = 0x15;
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P0_I2CBDAL = I2C_ADDR;
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P0_I2CBINT = BIT(5); // enable I2C B stop interrupt
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P0_EIE3 |= BIT(5); // enable I2C B interrupt
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@ -799,7 +861,7 @@ ack_ep0_setup:
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// push key change events to ep4 in
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if (!(P1_UDCEPBUF1CTRL & BIT(1)) && usb_key_change) {
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for (uint8_t i = 0; i < 12; i++)
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P1_UDCEP4BUFDATA = i2c_regs[i + 4];
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P1_UDCEP4BUFDATA = i2c_tx_buf[i + 4];
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P1_UDCEP4DATAINCNT = 12 - 1;
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P1_UDCEPBUF1CTRL |= BIT(1); // EP4 data ready
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@ -942,11 +1004,11 @@ void main(void)
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}
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// check for changes
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if (!memcmp(i2c_regs + 4, keys, 12))
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if (!memcmp(i2c_tx_buf + 4, keys, 12))
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continue;
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// signal interrupt
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memcpy(i2c_regs + 4, keys, 12);
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memcpy(i2c_tx_buf + 4, keys, 12);
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ext_int_assert();
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delay_us(100);
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ext_int_deassert();
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@ -954,7 +1016,7 @@ void main(void)
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#else
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//XXX: not figured out yet, not tested, not working
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if (scan_active) {
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uint8_t active_rows = keyscan_scan(i2c_regs + 4);
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uint8_t active_rows = keyscan_scan(i2c_tx_buf + 4);
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if (!active_rows) {
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scan_active = 0;
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keyscan_idle();
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@ -965,7 +1027,7 @@ void main(void)
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}
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// pressing FN+PINE+F switches to flashing mode (keys 1:2 3:5 5:2, electrically)
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if (i2c_regs[4 + 0] & BIT(2) && i2c_regs[4 + 2] & BIT(5) && i2c_regs[4 + 4] & BIT(2)) {
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if (i2c_tx_buf[4 + 0] & BIT(2) && i2c_tx_buf[4 + 2] & BIT(5) && i2c_tx_buf[4 + 4] & BIT(2)) {
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EA = 0;
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__asm__("mov r6,#0x5a");
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__asm__("mov r7,#0xe7");
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