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Fix issue with command parity, adding too many bits to command

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This commit is contained in:
Christian Molson 2020-12-09 16:22:38 -05:00
parent 011b585b0d
commit e48d343c5c
1 changed files with 8 additions and 2 deletions
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10
armsrc/em4x70.c
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@ -278,12 +278,18 @@ static void em4x70_send_bit(int bit) {
/** /**
* em4x70_send_command without parity * em4x70_send_command
*/ */
static void em4170_send_command(uint8_t command) { static void em4170_send_command(uint8_t command) {
int parity = 0; int parity = 0;
int msb_bit = 0;
for (int i = 0; i < 4; i++) { // Non automotive EM4x70 based tags are 3 bits + 1 parity.
// So drop the MSB and send a parity bit instead after the command
if(command_parity)
msb_bit = 1;
for (int i = msb_bit; i < 4; i++) {
int bit = (command >> (3 - i)) & 1; int bit = (command >> (3 - i)) & 1;
em4x70_send_bit(bit); em4x70_send_bit(bit);
parity ^= bit; parity ^= bit;