8b10b issues

1 files changed, 0 insertions, 149 deletions

diff --git a/center_fw/src/protocol.c b/center_fw/src/protocol.c
deleted file mode 100644
index dfa0d3e..0000000
--- a/center_fw/src/protocol.c
+++ /dev/null
@@ -1,149 +0,0 @@
-/* Control protocol receiver sitting between 8b10b.c and logical protocol handlers */
-
-#include <unistd.h>
-#include "protocol.h"
-#include "8b10b.h"
-
-volatile uint32_t decoding_error_cnt = 0, protocol_error_cnt = 0;
-volatile bool backchannel_frame = 0;
-
-/* Reset the given protocol state and register the command definition given with it. */
-void reset_receiver(struct proto_rx_st *st, const struct command_if_def *cmd_if) {
-    st->rxpos = -1;
-    st->address = 5; /* FIXME debug code */
-    st->cmd_if = cmd_if;
-}
-
-/* Receive an 8b10b symbol using the given protocol state. Handle any packets matching the enclosed command definition.
- *
- * This method is called from adc.c during the last bit period of the symbol, just before the actual end of the symbol
- * and start of the next symbol.
- */
-void receive_symbol(struct proto_rx_st *st, int symbol) {
-
-    if (symbol == -K28_2) { /* Backchannel marker */
-        /* This symbol is inserted into the symbol stream at regular intervals.  It is not passed to the higher protocol
-         * layers but synchronizes the backchannel logic through all nodes. The backchannel works by a node putting a
-         * specified additional load of about 100mA (FIXME) on the line (1) or not (0) with all other nodes being
-         * silent.  The master can detect this additional current.  The backchannel is synchronized to the 8b10b frame
-         * being sent from the master, and the data is also 8b10b encoded. This means the backchannel is independent
-         * from the forward-channel.
-         *
-         * This means while the forward-channel (the line voltage) might go like the upper trace, the back-channel (the
-         * line current drawn by the node) might simultaneously look like the lower trace:
-         *
-         * Zoomed in on two master frames:
-         *
-         *                          |<---       D31.1      --->|  |<---      D03.6       --->|
-         *     Master -> Node       1  0  1  0  1  1  1  0  0  1  1  1  0  0  0  1  0  1  1  0
-         *        Voltage (V)  .../^^\__/^^\__/^^^^^^^^\_____/^^^^^^^^\________/^^\__/^^^^^\___...
-         *
-         *        Current (I)  ...\_____________________________/^^^^^V^^^^^^^^V^^V^^V^^^^^V^^\...
-         *     Node -> Master                     0                            1
-         *
-         *
-         * Zoomed out on two node frames, or twenty master frames:
-         *
-         *     Master -> Node     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |<- symbols, one after another
-         *        Voltage (V)  ...XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX...
-         *
-         *        Current (I)  ...___/^^^^^\__/^^\_____/^^\__/^^^^^\_____/^^\__/^^^^^\__/^^\___...
-         *     Node -> Master       0  1  1  0  1  0  0  1  0  1  1  0  0  1  0  1  1  0  1  0
-         *                          |<---       D22.2      --->|  |<---      D09.5       --->|
-         *
-         * Note that during backchannel transmissions only one node transmits at a time, and all nodes including the
-         * transmitter keep their LEDs blanked to allow the master to more easily demodulate the transmission.
-         *
-         * This means that:
-         *    * backchannel transmissions should be sparse (one per several regular symbols) to not affect brightness
-         *      too much
-         *    * backchannel transmissions should be spaced-out evenly and frequent enough to not cause visible flicker
-         *
-         * A consequence of this is that the backchannel has a bandwidth of only a fraction of the forward-channel. The
-         * master can dynamically adjust the frequency of the forward-channel and spacing of the backchannel markers.
-         * For 5kHz and 10% backchannel data (every tenth symbol being a backchannel symbol) the bandwidth works out to:
-         *
-         *      BW(forward-channel) = 5 [kHz] / 10 [8b10b] = 500 byte/s
-         *      BW(backchannel)     = 5 [kHz] / 10 [8b10b] / 10 [every 10th symbol] / 10 [8b10b again] = 5 byte/s
-         *
-         * Luckily, we only use the backchannel for monitoring anyway and at ~20byte per monitoring frame we can easily
-         * monitor a bus-load (heh!) of nodes once a minute, which is enough for our purposes.
-         */
-
-        /* Blank the LEDs for the next frame to keep the bus quiet during backchannel transmission. This happens on all
-         * nodes. */
-        backchannel_frame = true;
-        return; /* We're done handling this symbol */
-    } else {
-        /* On anything else than a backchannel marker, turn off backchannel blanking for the next frame */
-        backchannel_frame = false;
-    }
-
-    if (symbol == -K28_1) { /* Comma/frame delimiter */
-        st->rxpos = 0;
-        /* Fall through and return and just ignore incomplete packets */
-
-    } else if (symbol == -DECODING_ERROR) {
-        if (decoding_error_cnt < UINT32_MAX)
-            decoding_error_cnt++;
-        goto reset;
-
-    } else if (symbol < 0) { /* Unknown comma symbol */
-        if (protocol_error_cnt < UINT32_MAX)
-            protocol_error_cnt++;
-        goto reset;
-
-    } else if (st->rxpos == -1) { /* Receiver freshly reset and no comma seen yet */
-        return;
-
-    } else if (st->rxpos == 0) { /* First data symbol, and not an error or comma symbol */
-        st->packet_type = symbol & ~PKT_TYPE_BULK_FLAG;
-        if (st->packet_type >= st->cmd_if->packet_type_max)
-            goto reset; /* Not a protocol error */
-
-        /* If this a bulk packet, calculate and store the offset of our portion of it. Otherwise just prime the state
-         * for receiving the indidual packet by setting the offset to the first packet byte after the address. */
-        int payload_len = st->cmd_if->payload_len[st->packet_type];
-        st->is_bulk = symbol & PKT_TYPE_BULK_FLAG;
-        st->offset = (st->is_bulk) ? (st->address*payload_len + 1) : 2;
-        st->rxpos++;
-
-        if (payload_len == 0 && st->is_bulk) {
-            /* Length-0 packet type, handle now for bulk packets as we don't know when the master will send the next
-             * comma or other symbol. For individually addressed packets, wait for the address byte. */
-            handle_command(st->packet_type, NULL);
-            goto reset;
-        }
-
-    } else if (!st->is_bulk && st->rxpos == 1) { /* First byte (address byte) of individually adressed packet */
-        if (symbol != st->address) /* A different node is adressed */
-            goto reset;
-
-        if (st->cmd_if->payload_len[st->packet_type] == 0) {
-            /* Length-0 packet type, handle now as we don't know when the master will send the next comma or other
-             * symbol. */
-            handle_command(st->packet_type, NULL);
-            goto reset;
-        }
-        st->rxpos++;
-
-    } else { /* Receiving packet body */
-        if (st->rxpos - st->offset >= 0) {
-            /* Either we're receiving an individually adressed packet adressed to us, or we're in the middle of a bulk
-             * packet at our offset */
-            st->argbuf[st->rxpos - st->offset] = symbol;
-        }
-        st->rxpos++;
-
-        if (st->rxpos - st->offset == st->cmd_if->payload_len[st->packet_type]) {
-            /* We're at the end of either an individual packet or our portion of a bulk packet. Handle packet here. */
-            handle_command(st->packet_type, (uint8_t *)st->argbuf);
-            goto reset;
-        }
-    }
-
-    return;
-reset:
-    st->rxpos = -1;
-}
-