Fixup/document I2C

This commit is contained in:
Ondrej Jirman 2021-06-19 02:51:23 +02:00
parent fbfa245ad4
commit 04ca071b09

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